Co-reporter:Zhi-Qiang Tan, Yong-Guang Yin, Xiao-Ru Guo, Meseret Amde, Myeong Hee Moon, Jing-Fu Liu, and Gui-Bin Jiang
Environmental Science & Technology November 7, 2017 Volume 51(Issue 21) pp:12369-12369
Publication Date(Web):October 11, 2017
DOI:10.1021/acs.est.7b03439
It is a great challenge to monitor the physical and chemical transformation of nanoparticles at environmentally relevant concentration levels, mainly because the commonly used techniques like dynamic light scattering and transmission electron microscopy are unable to characterize and quantify trace level nanoparticles in complex matrices. Herein, we demonstrate the on-line coupled system of hollow fiber flow field-flow fractionation (HF5), minicolumn concentration, and inductively coupled plasma mass spectrometry (ICPMS) detection as an efficient approach to study the aggregation and chemical transformation of silver nanoparticles (AgNPs) and ionic Ag species in the aqueous environment at ng/mL levels. Taking advantage of the in-line dialysis of HF5, the selective capture of Ag(I) species by the resin in minicolumn, and the high selectivity and sensitivity of ICPMS detection, we recorded the aggregation of 10 ng/mL AgNPs in complex matrices (e.g., NOM, Na+/Ca2+), revealing an interesting tiny AgNPs formation process of photoreduction of trace level Ag(I) that is different from larger AgNPs generated at high concentration of Ag(I) by accurate characterization and respectively identifying and quantifying new thiol-complexed Ag(I) and residual Ag(I) in the intertransformation of Ag(I) and AgNPs in domestic wastewater by simultaneously detecting the S and Ag signals via ICPMS.
Co-reporter:Zhineng Hao, Yongguang Yin, Dong Cao, and Jingfu Liu
Environmental Science & Technology May 16, 2017 Volume 51(Issue 10) pp:5464-5464
Publication Date(Web):April 25, 2017
DOI:10.1021/acs.est.6b03887
Photochemical halogenation of dissolved organic matter (DOM) may represent an important abiotic process for the formation of natural organobromine compounds (OBCs) and natural organoiodine compounds (OICs) within surface waters. Here we report the enhanced formation of OBCs and OICs by photohalogenating DOM in freshwater and seawater, as well as the noticeable difference in the distribution and composition pattern of newly formed OBCs and OICs. By using negative ion electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry, various OBCs and OICs were identified during the photohalogenation processes in sunlit waters. The respective number of OBCs and OICs formed in artificial seawater (ASW) under light radiation was higher than that in artificial freshwater (AFW), suggesting a possible role of the mixed reactive halogen species. OBCs were formed mainly via substitution reactions and addition reactions accompanied by other reactions and distributed into three classes: unsaturated hydrocarbons with relatively low oxygen content, unsaturated aliphatic compounds, and saturated fatty acids and carbohydrates with relatively high hydrogen content. Unlike the OBCs, OICs were located primarily in the region of carboxylic-rich alicyclic molecules composed of esterified phenolic, carboxylated, and fused alicyclic structures and were generated mainly through electrophilic substitution of the aromatic proton. Our findings call for further investigation on the exact structure and toxicity of the OBCs and OICs generated in the natural environment.
Co-reporter:Xiao-xia Zhou, Ying-jie Li, and Jing-fu Liu
ACS Sustainable Chemistry & Engineering June 5, 2017 Volume 5(Issue 6) pp:5468-5468
Publication Date(Web):April 12, 2017
DOI:10.1021/acssuschemeng.7b00797
Methods for the removal of silver nanoparticles (AgNPs) and their transformation products, silver-containing nanoparticles (AgCNPs), are important, because of their potential risks to the general population and the environment. In this study, aged iron oxide magnetic particles (IOMPs) were synthesized by a simple solvothermal reaction and used for the removal of AgCNPs. The prepared IOMPs exhibit a high adsorption capacity toward AgCNPs in aqueous medium. Kinetic studies indicated that the adsorption of AgCNPs is a pseudo-second-order process. The experimental data for the adsorption of AgCNPs follow the Langmuir isotherm model, and their maximum adsorption capacities were 19.9–62.8 mg/g at pH 6.2 and 298 K. The sorption mean free energy calculated by the Dubinin–Radushkevich isotherm was 4.09–5.17 kJ/mol, indicating the occurrence of physisorption, which was mainly due to the electrostatic interactions. The IOMP adsorbents maintained high removal efficiencies after four cycles of adsorption–desorption, suggesting good reusability of the developed IOMPs. Moreover, good removal efficiencies (63.3%–99.9%) and recoveries (67.1%–99.9%) were obtained from the real samples spiked with AgCNPs at levels of 10 μg/L, showing that the aged IOMPs could be used as efficient and low-cost adsorbents for the removal and recovery of AgCNPs from real waters.Keywords: Adsorption; Aged iron oxide magnetic particles; Removal; Silver-containing nanoparticles; Waters;
Co-reporter:Fengqiong Shi, Jingfu Liu
Journal of Chromatography A 2017 Volume 1507(Volume 1507) pp:
Publication Date(Web):21 July 2017
DOI:10.1016/j.chroma.2017.06.002
•The first report on the determination of lipophilicity and dissociation constants of dialkyl phosphinic acids (DPAs).•The measured log KOW and pKa values were compared with the predicted ones.•ACD/pKa DB and KOWWIN show good accuracy in predicting pKa and KOW of DPAs.Determination of the physicochemical properties, especially the lipophilicity (expressed as the logarithm of distribution coefficient, log D) and dissociation constant (pKa), is of great importance in the early stage of environmental risk assessment for an ionizable compound without these data. Currently, the log D and pKa values of dialkyl phosphinic acids (DPAs), the environmental hydrolysates of aluminum dialkyl phosphinates (ADPs) that is one class of emerging phosphorus-containing flame retardants, are not available. In this study, the log D and pKa values of three DPAs including methylethylphosphinic acid (MEPA), diethylphosphinic acid (DEPA) and methylcyclohexyl phosphinic acid (MHPA), were simultaneously determined by negligible depletion hollow fiber supported liquid phase microextraction (nd-HF-LPME) followed by ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC–MS/MS). The pKa and log D of DPAs were determined by curve-fitting the experimental data with equations derived on the basis of the Henderson-Hasselbalch equation and compared with model calculated data. For MEPA, DEPA and MHPA, the pKa values were close and around 3, but the log Ds were strongly pH-dependent with values from −5.01 to 1.01. The log KOW of the neutral form (log KOW,HA) and ionic form (log KOW,A) were in the range of −0.67–1.02 and −3.86–−1.33, respectively. The experimentally determined pKa values were highly in good agreement with ACD/pKa predicted values and the measured log KOW,HA values were closely related to KOWWIN calculated ones, suggesting ACD/pKa and KOWWIN are good alternative methods to estimate pKa and log KOW of DPAs, respectively. As far as we know, this is the first report on the pKa and log D data for DPAs, which are fundamental for the product design and evaluating the environmental behavior and effects of DPAs and ADPs.
Co-reporter:Dan Zhang, Yongguang Yin, Yanbin Li, Yong Cai, Jingfu Liu
Science of The Total Environment 2017 Volume 578(Volume 578) pp:
Publication Date(Web):1 February 2017
DOI:10.1016/j.scitotenv.2016.10.222
•NOM can significantly inhibit the Fe3 +-induced degradation of MeHg.•High molecular weight NOM shows higher light attenuation-induced degradation inhibition.•Photodegradation-mediated by NOM is also affected by pH and co-existing Cl− and NO3−.Photodegradation is the main depletion pathway of methylmercury (MeHg) in surface water. However, the underlying mechanism of MeHg photodegradation is still not well understood. In this study, the critical role of natural organic matter (NOM) from Suwannee River natural organic matter of the International Humic Substance Society, especially its molecular weight, and the impacts of other related environmental factors in MeHg photodegradation were investigated. We observed that MeHg cannot photo-degrade in de-ionized water, excluding the direct photodegradation of MeHg. While either NOM or Fe3 + alone induced MeHg photodegradation, co-existing NOM significantly inhibited the Fe3 +-induced degradation, highlighting the critical and complex role of NOM in MeHg photodegradation. Additionally, MeHg exhibited different photodegradation rates in the presence of molecular weight fractionated natural organic matter (Mf-NOM). More importantly, high concentration of NOM caused light attenuation significantly inhibited the photodegradation of MeHg, which was more significant for high molecular weight Mf-NOM. In the presence of Mf-NOM, MeHg photodegradation was also affected by light quality, pH and co-existing Cl− and NO3−. The study is helpful for a better understanding of the critical role of NOM and other environmental factors on MeHg photodegradation in surface water.Download high-res image (189KB)Download full-size image
Co-reporter:Tesfaye Tolessa, Xiao-Xia Zhou, Meseret Amde, Jing-Fu Liu
Talanta 2017 Volume 169(Volume 169) pp:
Publication Date(Web):1 July 2017
DOI:10.1016/j.talanta.2017.03.064
•Monodisperse magnetic chitosan microspheres (MCMs) were synthesized and characterized.•Adsorption and desorption conditions for extraction of silver nanoparticles (AgNPs) by the MCMs were optimized.•The MCMs exhibited selective sensitivity for AgNPs in the presence of the ionic counterparts.•The MCMs showed high performance in extraction of AgNPs from environmental waters.Solid-phase extraction (SPE) based on reusable magnetic chitosan microspheres was coupled with ICP-MS for separation and quantification of silver nanoparticles (AgNPs) in the presence of silver ions in environmental water samples. The monodisperse magnetic chitosan microspheres with an average size of 2 µm were engineered using suspension cross-linking technique, and characterized and investigated for its application as SPE adsorbent. Parameters affecting the SPE were optimized, and the best performance was achieved by extracting a 20 mL sample (pH 4.5) with 10 mg adsorbent for 90 min, followed by elution with 1 mL 1% (w/v) thiourea in 10% (v/v) nitric acid for 10 min. The detection limit, calculated as 3 s (s, standard deviation for 11 blank readings), for three AgNPs coated with polyvinyl pyrrolidone (PVP), citrate and polyvinyl alcohol (PVA) and sizes of 31, 40, 46 nm, respectively, were in the range of 0.016‒0.023 μg/L. The repeatability and reproducibility (RSD, n=7) at a spiking level of 0.1 μg/L AgNPs were 4.2% and 8.1%, respectively. The developed method has been applied in the analysis of AgNPs in river, lake and wastewater samples, with excellent extraction efficiencies (84.9‒98.8%) for AgNPs at spiking levels of 0.86 and 8.70 μg/L. The cationic chitosan microspheres showed good species selectivity and reusability for extraction of AgNPs in the presence of Ag+, and hence the proposed method is simple, cost effective and environmentally friendly.Download high-res image (107KB)Download full-size image
Co-reporter:Yongguang Yin, Zhiqiang Tan, Ligang Hu, Sujuan Yu, Jingfu LiuGuibin Jiang
Chemical Reviews 2017 Volume 117(Issue 5) pp:
Publication Date(Web):February 17, 2017
DOI:10.1021/acs.chemrev.6b00693
The rapidly growing applicability of metal-containing engineered nanoparticles (MENPs) has made their environmental fate, biouptake, and transformation important research topics. However, considering the relatively low concentration of MENPs and the high concentration of background metals in the environment and in organisms, tracking the fate of MENPs in environment-related scenarios remains a challenge. Intrinsic labeling of MENPs with radioactive or stable isotopes is a useful tool for the highly sensitive and selective detection of MENPs in the environment and organisms, thus enabling tracing of their transformation, uptake, distribution, and clearance. In this review, we focus on radioactive/stable isotope labeling of MENPs for their environmental and biological tracing. We summarize the advantages of intrinsic radioactive/stable isotopes for MENP labeling and discuss the considerations in labeling isotope selection and preparation of labeled MENPs, as well as exposure routes and detection of labeled MENPs. In addition, current practice in the use of radioactive/stable isotope labeling of MENPs to study their environmental fate and bioaccumulation is reviewed. Future perspectives and potential applications are also discussed, including imaging techniques for radioactive- and stable-isotope-labeled MENPs, hyphenated multistable isotope tracers with speciation analysis, and isotope fractionation as a MENP tracer. It is expected that this critical review could provide the necessary background information to further advance the applications of isotope tracers to study the environmental fate and bioaccumulation of MENPs.
Co-reporter:Deribachew Bekana, Rui LiuMeseret Amde, Jing-Fu Liu
ACS Applied Materials & Interfaces 2017 Volume 9(Issue 1) pp:
Publication Date(Web):December 16, 2016
DOI:10.1021/acsami.6b15378
It is still a great challenge to develop simple and low-cost methods for preparation of surface-enhanced Raman scattering (SERS) substrates with high sensitivity and reproducibility. Taking advantage of the microstructure of polycrystalline ice, we developed a new method to assemble large area gold nanoparticle (AuNP) superstructures as SERS substrates without external templating and aggregating agent. The assembly was conducted by freezing AuNP colloid at −20 °C, which concentrated AuNPs in the ice veins and produced an AuNP superstructure upon thawing the ice. The AuNP superstructures exhibited high SERS activity with enhancement factors on the order of 7.63 × 107 owing to the high-density hot spots throughout the superstructures. The SERS activity was found to increase with particle size and aggregate size of AuNP superstructures. Besides, the substrates showed good uniformity and reproducibility with relative standard deviations of 11.9% and 12.4%, respectively. The substrates showed long-term stability, maintaining SERS activity over a period of five months without noticeable change in morphology of the superstructures. The substrates was further used for label-free detection of trace Thiram on apple fruit with high sensitivity down to the concentration of 0.28 ng/cm2, offering great potential to monitor Thiram levels in foodstuffs and environmental samples.Keywords: aggregate size; microstructure; polycrystalline ice; self-assembly; superstructure; veins;
Co-reporter:Yongguang Yin, Wei Xu, Zhiqiang Tan, Yanbin Li, Weidong Wang, Xiaoru Guo, Sujuan Yu, Jingfu Liu, Guibin Jiang
Environmental Pollution 2017 Volume 220, Part B(Volume 220, Part B) pp:
Publication Date(Web):1 January 2017
DOI:10.1016/j.envpol.2016.10.081
•Transformation of AgCl into AgNP under sunlight in the presence of organic matter.•Transformation of AgCl/Ag2S into ionic/elemental Ag under incineration.•Transformation of Ag2S and AgCl is a possible source of natural AgNP.•Risk of ionic Ag/AgNP in utilization of incineration residues should be assessed.AgCl and Ag2S prevalently exist in the environment as minerals and/or the chlorination and sulfidation products of ionic silver and elemental silver nanoparticles (AgNPs). In this work, we investigated the chemical transformation of AgCl and Ag2S under simulated sunlight (in water) and incineration (in sludge and simulated municipal solid waste, SMSW). In the presence of natural organic matter, AgCl in river water was observed to be transformed into AgNPs under simulated sunlight, while photo-reduction of Ag2S could not take place under the same experimental conditions. During the course of incineration, pure Ag2S was transformed into elemental silver while AgCl remained stable; however, both Ag2S in sludge and AgCl in SMSW can be transformed to elemental silver under incineration, evident by the results of X-ray absorption spectroscopy and scanning electron microscopy measurements. Incineration temperature played an important role in the transformation of Ag2S and AgCl into elemental silver. These results suggest that chemical transformations of Ag2S and AgCl into elemental silver could be a possible source of naturally occurring or unintentionally produced AgNPs, affecting the fate, transport, bioavailability and toxicity of silver. Therefore, it is necessary to include the contributions of this transformation process when assessing the risk of ionic silver/AgNPs and the utilization and management of incineration residues.Chemical transformations of Ag2S and AgCl into elemental silver could be a possible source of naturally occurring or unintentionally produced AgNPs.Download high-res image (168KB)Download full-size image
Co-reporter:Meseret Amde, Jing-fu Liu, Zhi-Qiang Tan, Deribachew Bekana
Environmental Pollution 2017 Volume 230(Volume 230) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.envpol.2017.06.064
•Current state-of-the-knowledge on the transformation and bioavailability of MeO-NPs in the environment has been provided.•Effects of MeO-NPs behavior on their transformations have been reviewed.•Role of the transformation processes on bioavailability of the NPs have been discussed.•Future research directions required to fill the existing research gaps have been provided.Metal oxide nanoparticles (MeO-NPs) are among the most consumed NPs and also have wide applications in various areas which increased their release into the environmental system. Aquatic (water and sediments) and terrestrial compartments are predicted to be the destination of the released MeO-NPs. In these compartments, the particles are subjected to various dynamic processes such as physical, chemical and biological processes, and undergo transformations which drive them away from their pristine state. These transformation pathways can have strong implications for the fate, transport, persistence, bioavailability and toxic-effects of the NPs. In this critical review, we provide the state-of-the-knowledge on the transformation processes and bioavailability of MeO-NPs in the environment, which is the topic of interest to researchers. We also recommend future research directions in the area which will support future risk assessments by enhancing our knowledge of the transformation and bioavailability of MeO-NPs.Download high-res image (245KB)Download full-size image
Co-reporter:Zhen Zhang, Kun Zeng, Jingfu Liu
TrAC Trends in Analytical Chemistry 2017 Volume 87() pp:49-57
Publication Date(Web):February 2017
DOI:10.1016/j.trac.2016.12.002
•Immunochemical detection of emerging organic contaminants in waters is reviewed.•Techniques in development of antibodies and other binders against EOCs were described.•Antibody-based analytical methods for EOCs such as ELISA and TRFIA are reviewed.•Immunosensor techniques to carry out on-site analysis on single samples are overviewed.Immunochemical techniques exhibit great advantages of high efficiency, rapidness, reliability and low cost compared to instrumental methods for monitoring emerging organic contaminants (EOCs) in aquatic environments. This review covers recent advances in applying traditional and other antibody-like binders against these organic pollutants, and various antibody-based immunochemical methods such as enzyme-linked immunosorbent assays, time-resolved fluoroimmunoassay and immunosensors. Moreover, we also discuss the advantages and disadvantages of techniques for antibody production and analytical methods, and covers promising future prospects.
Co-reporter:Rui Liu, Jing-Fu Liu, Li-Qiang Zhang, Jie-Fang Sun and Gui-Bin Jiang
Journal of Materials Chemistry A 2016 vol. 4(Issue 20) pp:7606-7614
Publication Date(Web):10 Mar 2016
DOI:10.1039/C6TA01217E
Here, we report a versatile and simple route for the preparation of graphene-like, single-crystalline superparamagnetic γ-Fe2O3 nanosheets (NSs) as superior inorganic arsenic sorbents. Benefiting from their large surface area and abundant hydroxyl groups, γ-Fe2O3 NSs can sequestrate up to 109.5 and 39.1 mg g−1 of As(III) and As(V) ions within 15 min. Moreover, after screening the electrostatic repulsion, ca., through the introduction of a salt or changing solution pH, the removal efficiency of As(V) was enhanced to that of As(III). Besides showing similar adsorption capacity, O1s XPS and As K-edge EXAFS revealed that As(III) and As(V) are captured on the γ-Fe2O3 NSs via the formation of an identical but uncommon monodentate mononuclear (1V) complex. Such a configuration is favorable for the accommodation of more arsenic ions, and therefore reduces the surface energy of the ultrathin NSs more effectively than other complexion modes. Our study demonstrates the feasibility of solving an environmental problem through material innovation, and the foreground of application of 2D materials for environmental improvement.
Co-reporter:Ji-jun Tang, Jie-fang Sun, Rui Lui, Zong-mian Zhang, Jing-fu Liu, and Jian-wei Xie
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 3) pp:2449
Publication Date(Web):December 31, 2015
DOI:10.1021/acsami.5b12860
Quick and accurate on-site detection of active ricin has very important realistic significance in view of national security and defense. In this paper, optimized single-stranded oligodeoxynucleotides named poly(21dA), which function as a depurination substrate of active ricin, were screened and chemically attached on gold nanoparticles (AuNPs, ∼100 nm) via the Au–S bond [poly(21dA)–AuNPs]. Subsequently, poly(21dA)–AuNPs were assembled on a dihydrogen lipoic-acid-modified Si wafer (SH–Si), thus forming the specific surface-enhanced Raman spectroscopy (SERS) chip [poly(21dA)–AuNPs@SH–Si] for depurination of active ricin. Under optimized conditions, active ricin could specifically hydrolyze multiple adenines from poly(21dA) on the chip. This depurination-induced composition change could be conveniently monitored by measuring the distinct attenuation of the SERS signature corresponding to adenine. To improve sensitivity of this method, a silver nanoshell was deposited on post-reacted poly(21dA)–AuNPs, which lowered the limit of detection to 8.9 ng mL–1. The utility of this well-controlled SERS chip was successfully demonstrated in food and biological matrices spiked with different concentrations of active ricin, thus showing to be very promising assay for reliable and rapid on-site detection of active ricin.Keywords: active ricin; depurination; gold nanoparticles; on-site detection; surface-enhanced Raman spectroscopy
Co-reporter:Xiaoru Guo, Yongguang Yin, Zhiqiang Tan, Zongmian Zhang, Yongsheng Chen, and Jingfu Liu
Environmental Science & Technology Letters 2016 Volume 3(Issue 10) pp:381-385
Publication Date(Web):August 12, 2016
DOI:10.1021/acs.estlett.6b00271
Water surface microlayer (SML), as the interface between water and the atmosphere, shows distinct physicochemical properties that differ from those of underlying water. Herein, for the first time, we demonstrate the SML enrichment of nanoparticles (NPs) by using silver nanoparticles (AgNPs) as a model via indoor experiments. The occurrence of SML enrichment of AgNPs was confirmed by the increased concentration of NPs in the SML relative to that in the bulk phase, and the in situ recording of the enhanced Raman spectroscopy intensity of a probe adsorbed on AgNPs in the SML. The significant enrichment of NPs is strongly influenced by environmentally relevant factors such as the solution pH, ionic strength, and natural organic matter. Additionally, the SML enrichment factor was estimated to be 14.6–26.5 for AgNPs in natural waters. Our findings indicate that NPs are inclined to accumulate in the SML, which could cause environmental effects that are differential to the bulk phase.
Co-reporter:Yongguang Yin, Xiaoya Yang, Ligang Hu, Zhiqiang Tan, Lixia Zhao, Zhen Zhang, Jingfu Liu, and Guibin Jiang
Environmental Science & Technology Letters 2016 Volume 3(Issue 4) pp:160-165
Publication Date(Web):March 22, 2016
DOI:10.1021/acs.estlett.6b00066
The biosynthesis of silver nanoparticles (AgNPs) by microorganisms has become a hot topic in recent years, although its mechanism is still not well understood. Here we report the extracellular biosynthesis of AgNPs by the fungus Fusarium oxysporum through a superoxide-dependent mechanism. Reduction of Ag+ to AgNPs in the extracellular region of F. oxysporum was verified by transmission electron microscopy, while the superoxide produced extracellularly by F. oxysporum was evidenced by chemiluminescence. We further demonstrated that the biosynthesis of AgNPs was inhibited by a superoxide scavenger or the inhibitor of NADH oxidases, and the addition of NADH significantly improved the formation of AgNPs. These results demonstrated that, for the first time, the fungus F. oxysporum can mediate the synthesis of AgNPs through the enzymatic generation of extracellular superoxide, which is helpful in understanding the biosynthesis of AgNPs and the biomineralization and transformation of silver and other metals or metalloids.
Co-reporter:Fengqiong Shi, Jingfu Liu, Kang Liang, Rui Liu
Journal of Chromatography A 2016 Volume 1447() pp:9-16
Publication Date(Web):20 May 2016
DOI:10.1016/j.chroma.2016.04.021
•Ionic liquid [HMIM][FAP] was used as a SPME coating for the first time.•High hydrophobicity and thermostability make [HMIM][FAP] an excellent SPME coating.•[HMIM][FAP]-based SPME fiber exhibits superior stability and durability.•This SPME fiber shows good extraction efficiencies and enrichment factors for OPEs.Ionic liquids (ILs) containing the tris(pentafluoroethyl)trifluorophosphate [FAP] anion and various cations have great potential in sample preparation because of their excellent hydrophobicity, thermostability and low hydrolysity. In the present study, a [FAP]-based IL, 1-hexyl-3-methylimidazolium tris (pentafluoroethyl) trifluoro phosphate ([HMIM][FAP]), was used as coatings of solid-phase microextraction (SPME) for extracting organophosphate esters (OPEs) from environmental water samples. This SPME fiber was fabricated by coating a stainless steel wire substrate with [HMIM][FAP] via a simple direct dip-coating approach, and the extraction was conducted by the direct immersion solid phase microextraction. Coupling to gas chromatography mass spectrometry (GC–MS), the developed SPME method exhibited excellent selectivity and sensitivity towards the extraction of 11 OPEs from aqueous samples. Satisfactory linearity (R2 ≥ 0.99) of the calibration curves was obtained over the range of 0.05–50.0 ng mL−1 with the limits of detection (LODs, S/N = 3) and limits of quantification (LOQs, S/N = 10) ranged from 0.13–7.40 ng L−1 and 0.50–24.0 ng L−1, respectively. The proposed SPME method showed excellent extraction efficiency to OPEs with enrichment factors in the range of 168–2603, and acceptable reproducibility with relative standard deviations (RSDs) ≤15% for single fiber (n = 7) and ≤16% for fiber-to-fiber (n = 3 × 3) at a concentration level of 0.5 ng mL−1, respectively. The prepared IL-based fiber was successfully applied to determine eleven common used OPEs in tap water, influent and effluent of sewage treatment plant, with results are comparable to those determined by the reference (UPLC–MS/MS), and spiked recoveries in the range of 84.0–108%, 82.1–123% and 82.8–100%, respectively.
Co-reporter:Sujuan Yu, Yongguang Yin, Xiaoxia Zhou, Lijie Dong and Jingfu Liu
Environmental Science: Nano 2016 vol. 3(Issue 4) pp:883-893
Publication Date(Web):24 Jun 2016
DOI:10.1039/C6EN00104A
Silver nanoparticles (AgNPs) are rather mutable in water columns, and the oxidation of AgNPs to release Ag+ and reduction of Ag+ to regenerate AgNPs exist simultaneously in certain environments, making it rather difficult to monitor the reaction kinetics. In this study, we synthesized isotopically labeled AgNPs (99.5% 107Ag, 107AgNPs) and AgNO3 (99.81% 109Ag, 109AgNO3). For the first time, two stable Ag isotopes were used in the same experiment to track the transformation kinetics of AgNPs and Ag+ independently in aquatic environments. It was found that the oxidation of AgNPs dominated the reaction in simple water solutions containing both 107AgNPs and 109Ag+. Sunlight significantly accelerated the dissolution of the 107AgNPs, but longer solar irradiation (8 h) triggered aggregation of the 107AgNPs and therefore reduced the reaction rate. With the addition of 5 mg C L−1 dissolved organic matter, the reduction of 109Ag+ played the leading role. The corrected concentration of dissolved 107Ag+ began to decrease after some time, indicating other reduction mechanisms were happening. An elevated pH (pH 8.5) could even completely inhibit the oxidation of 107AgNPs. All the reactions seemed stalled at low temperature (6 °C) except the dissolution of 107AgNPs under solar irradiation, suggesting a non-negligible effect of sunlight. The presence of divalent cations induced agglomeration of 107AgNPs, but the reduction of 109Ag+ was not significantly affected. These findings implied that the transformation between AgNPs and Ag+ was rather complex and greatly depended on the external conditions. Given the fact that Ag+ has been shown to be much more toxic than AgNPs, the speciation change may dramatically impact the final toxicity and bioavailability of AgNPs, so there is a high demand for assessing the environmental risks of AgNPs under more realistic conditions.
Co-reporter:Meseret Amde, Jing-Fu Liu, Zhi-Qiang Tan, Deribachew Bekana
Talanta 2016 Volume 149() pp:341-346
Publication Date(Web):1 March 2016
DOI:10.1016/j.talanta.2015.12.004
•ZnO nanofluid based vortex assisted liquid liquid microextraction was developed.•Hg2+ in waters was extracted prior to CV-AFS detection.•Free from dispersive solvent and no requirement of back extraction.•The method is simple, fast, inexpensive and environmental friendly.Zinc oxide nanofluid (ZnO-NF) based vortex assisted liquid liquid microextraction (ZnO-NF VA-LLME) was developed and employed in extraction of inorganic mercury (Hg2+) in environmental water samples, followed by cold vapor atomic fluorescence spectrometry (CV-AFS). Unlike other dispersive liquid liquid microextraction techniques, ZnO-NF VA-LLME is free of volatile organic solvents and dispersive solvent consumption. Analytical signals were obtained without back-extraction from the ZnO-NF phase prior to CV-AFS determination. Some essential parameters of the ZnO-NF VA-LLME and cold vapor generation such as composition and volume of the nanofluid, vortexing time, pH of the sample solution, amount of the chelating agent, ionic strength and matrix interferences have been studied. Under optimal conditions, efficient extraction of 1 ng/mL of Hg2+ in 10 mL of sample solution was achieved using 50 μL of ZnO-NF. The enrichment factor before dilution, detection limits and limits of quantification of the method were about 190, 0.019 and 0.064 ng/mL, respectively. The intra and inter days relative standard deviations (n=8) were found to be 4.6% and 7.8%, respectively, at 1 ng/mL spiking level. The accuracy of the current method was also evaluated by the analysis of certified reference materials, and the measured Hg2+ concentration of GBW08603 (9.6 ng/mL) and GBW(E)080392 (8.9 ng/mL) agreed well with their certified value (10 ng/mL). The method was applied to the analysis of Hg2+ in effluent, influent, lake and river water samples, with recoveries in the range of 79.8–92.8% and 83.6–106.1% at 1 ng/mL and 5 ng/mL spiking levels, respectively. Overall, ZnO-NF VA-LLME is fast, simple, cost-effective and environmentally friendly and it can be employed for efficient enrichment of the analyte from various water samples.
Co-reporter:Jiefang Sun, Rui Liu, Jijun Tang, Zongmian Zhang, Xiaoxia Zhou, and Jingfu Liu
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 30) pp:16730
Publication Date(Web):July 13, 2015
DOI:10.1021/acsami.5b04449
Here, we report an efficient and facile method for constructing plasmonic gold nanostructures with controlled morphology on a Si wafer and its use as a surface enhanced Raman scattering (SERS) reporting system for specific detection of HClO. To achieve this substrate, the core gold nanoparticles (AuNPs, ∼100 nm) with a monolayer of 4-mercaptoimidazole (MI) ligands were covalently linked to a thiol-derived Si wafer (MI-AuNPs@SH-Si). Taking advantage of the intermolecular NH···N hydrogen bond (HB) provided by the neighboring imidazole moiety, multiple satellite AuNPs (∼12 nm) decorated with both MI and a Raman reporter are assembled around the core MI-AuNPs at pH 5.0. The uniform morphology of the AuNP-based nanostructures on the Si wafer offer a high density of hot spots with good SERS performance for detecting HClO. The fast oxidation of the imidazole moieties by HClO causes HB destruction and therefore separation of the satellite AuNPs from the core AuNPs, which gives rise to SERS signal damping of the chip that is employed for HClO analysis. This simple and cost-effective method is highly selective for HClO over common interferences and several reactive oxygen/nitrogen species, and enabled rapid analysis at concentrations as low as 1.2 μmol L–1. The present approach is applied to analyze water and human serum samples with satisfactory results.Keywords: gold nanoparticles; hydrogen bonding; hypochlorous acid; imidazole; surface-enhanced Raman scattering
Co-reporter:Rui Liu, Jie-fang Sun, Dong Cao, Li-qiang Zhang, Jing-fu Liu and Gui-bin Jiang
Chemical Communications 2015 vol. 51(Issue 7) pp:1309-1312
Publication Date(Web):18 Nov 2014
DOI:10.1039/C4CC08016E
In this report, we propose and demonstrate the fabrication of a highly-specific SERS substrate, which was achieved by the co-precipitation of functional materials, such as nanosorbents and nanocatalysts, into Ag nanoporous films. Based on the nanostructures developed, we performed the ultrasensitive detection of arsenic ions by SERS and monitored the catalyzed reactions using real-time SERS.
Co-reporter:Zhi-Qiang Tan, Jing-Fu Liu, Xiao-Ru Guo, Yong-Guang Yin, Seul Kee Byeon, Myeong Hee Moon, and Gui-Bin Jiang
Analytical Chemistry 2015 Volume 87(Issue 16) pp:8441
Publication Date(Web):July 29, 2015
DOI:10.1021/acs.analchem.5b01827
The intertransformation of silver nanoparticles (AgNPs) and ionic silver (Ag(I)) in the environment determines their transport, uptake, and toxicity, demanding methods to simultaneously separate and quantify AgNPs and Ag(I). For the first time, hollow fiber flow field-flow fractionation (HF5) and minicolumn concentration were on-line coupled together with multiple detectors (including UV–vis spectrometry, dynamic light scattering, and inductively coupled plasma mass spectrometry) for full spectrum separation, characterization, and quantification of various Ag(I) species (i.e., free Ag(I), weak and strong Ag(I) complexes) and differently sized AgNPs. While HF5 was employed for filtration and fractionation of AgNPs (>2 nm), the minicolumn packed with Amberlite IR120 resin functioned to trap free Ag(I) or weak Ag(I) complexes coming from the radial flow of HF5 together with the strong Ag(I) complexes and tiny AgNPs (<2 nm), which were further discriminated in a second run of focusing by oxidizing >90% of tiny AgNPs to free Ag(I) and trapped in the minicolumn. The excellent performance was verified by the good agreement of the characterization results of AgNPs determined by this method with that by transmission electron microscopy, and the satisfactory recoveries (70.7–108%) for seven Ag species, including Ag(I), the adduct of Ag(I) and cysteine, and five AgNPs with nominal diameters of 1.4 nm, 10 nm, 20 nm, 40 nm, and 60 nm in surface water samples.
Co-reporter:Yongguang Yin, Mohai Shen, Zhiqiang Tan, Sujuan Yu, Jingfu Liu, and Guibin Jiang
Environmental Science & Technology 2015 Volume 49(Issue 11) pp:6581-6589
Publication Date(Web):May 5, 2015
DOI:10.1021/es5061287
Ubiquitous natural organic matter (NOM) plays an important role in the aggregation state of engineered silver nanoparticles (AgNPs) in aquatic environment, which determines the transport, transformation, and toxicity of AgNPs. As various capping agents are used as coatings for nanoparticles and NOM are natural polymer mixture with wide molecular weight (MW) distribution, probing the particle coating-dependent interaction of MW fractionated natural organic matter (Mf-NOM) with various coatings is helpful for understanding the differential aggregation and transport behavior of engineered AgNPs as well as other metal nanoparticles. In this study, we investigated the role of pristine and Mf-NOM on the aggregation of AgNPs with Bare, citrate, and PVP coating (Bare-, Cit-, and PVP-AgNP) in mono- and divalent electrolyte solutions. We observed that the enhanced aggregation or dispersion of AgNPs in NOM solution highly depends on the coating of AgNPs. Pristine NOM inhibited the aggregation of Bare-AgNPs but enhanced the aggregation of PVP-AgNPs. In addition, Mf-NOM fractions have distinguishing roles on the aggregation and dispersion of AgNPs, which also highly depend on the AgNPs coating as well as the MW of Mf-NOM. Higher MW Mf-NOM (>100 kDa and 30–100 kDa) enhanced the aggregation of PVP-AgNPs in mono- and divalent electrolyte solutions, whereas lower MW Mf-NOM (10–30 kDa, 3–10 kDa and <3 kDa) inhibited the aggregation of PVP-AgNPs. However, all the Mf-NOM fractions inhibited the aggregation of Bare-AgNPs. For PVP- and Bare-AgNPs, the stability of AgNPs in electrolyte solution was significantly correlated to the MW of Mf-NOM. But for Cit-AgNPs, pristine NOM and Mf-NOM has minor influence on the stability of AgNPs. These findings about significantly different roles of Mf-NOM on aggregation of engineered AgNPs with various coating are important for better understanding of the transport and subsequent transformation of AgNPs in aquatic environment.
Co-reporter:Meseret Amde, Jing-Fu Liu, and Long Pang
Environmental Science & Technology 2015 Volume 49(Issue 21) pp:12611-12627
Publication Date(Web):October 7, 2015
DOI:10.1021/acs.est.5b03123
Ionic liquids (ILs) comprise mostly of organic salts with negligible vapor pressure and low flammability that are proposed as replacements for volatile solvents. ILs have been promoted as “green” solvents and widely investigated for their various applications. Although the utility of these chemicals is unquestionable, their toxic effects have attracted great attention. In order to manage their potential hazards and design environmentally benign ILs, understanding their environmental behavior, fate and effects is important. In this review, environmentally relevant issues of ILs, including their environmental application, environmental behavior and toxicity are addressed. In addition, also presented are the influence of ILs on the environmental fate and toxicity of other coexisting contaminants, important routes for designing nontoxic ILs and the techniques that might be adopted for the removal of ILs.
Co-reporter:Jing-Bo Chao, Xiao-Xia Zhou, Mo-Hai Shen, Zhi-Qiang Tan, Rui Liu, Su-Juan Yu, Xiao-Wei Wang, and Jing-Fu Liu
Environmental Science & Technology 2015 Volume 49(Issue 24) pp:14213-14220
Publication Date(Web):November 18, 2015
DOI:10.1021/acs.est.5b02917
Hollow fiber supported liquid membrane (HFSLM) extraction was coupled with ICP-MS for speciation analysis of labile Ag(I) and total Ag(I) in dispersions of silver nanoparticles (AgNPs) and environmental waters. Ag(I) in aqueous samples was extracted into the HFSLM of 5%(m/v) tri-n-octylphosphine oxide in n-undecane, and stripped in the acceptor of 10 mM Na2S2O3 and 1 mM Cu(NO3)2 prepared in 5 mM NaH2PO4–Na2HPO4 buffer (pH 7.5). Negligible depletion and exhaustive extraction were conducted under static and 250 rpm shaking to extract the labile Ag(I) and total Ag(I), respectively. The extraction equilibration was reached in 8 h for both extraction modes. The extraction efficiency and detection limit were (2.97 ± 0.25)% and 0.1 μg/L for labile Ag(I), and (82.3 ± 2.0)% and 0.5 μg/L for total Ag(I) detection, respectively. The proposed method was applied to determine labile Ag(I) and total Ag(I) in different sized AgNP dispersions and real environmental waters, with spiked recoveries of total Ag(I) in the range of 74.0–98.1%. With the capability of distinguishing labile and total Ag(I), our method offers a new approach for evaluating the bioavailability and understanding the fate and toxicity of AgNPs in aquatic systems.
Co-reporter:Yu-Min Niu, Yong Liang, Ji-Yan Liu, Jing-Fu Liu
Journal of Chromatography A 2015 Volume 1394() pp:26-35
Publication Date(Web):15 May 2015
DOI:10.1016/j.chroma.2015.03.041
•First report on the determination of dialkyl phosphinate acids in waters.•Identification and quantification by ion chromatography tandem mass spectrometry.•SPE cleanup and large volume sample injection offer high sensitivity.•Applicable for various environmental samples with high sensitivity.Dialkyl phosphinate acids (DPAs) are the hydrolysates of aluminum dialkyl phosphinates (ADPs), one class of emerging phosphorus flame retardants since brominated flame retardants have been gradually phased out in recent years. It has been found that once dissolved in water, ADPs are completely hydrolyzed and exist as DPAs. However, there is no report on the determination of DPAs in environmental water samples. For the first time, we developed a method for the analysis of trace DPAs and ADPs in different environmental samples, including waters, soils and sediments. In this proposed method, MAX cartridges were employed for the purification, and ion chromatography (IC) tandem mass spectrometry (MS) method with large volume injection (200 μL) and postcolumn addition of methanol and NH3·H2O were employed for the determination of DPAs and ADPs. The matrix effects were <16% for water samples and <25% for soil/sediment samples, which were greatly improved in comparison to the liquid chromatography (LC) tandem MS determination. Determined at three fortified levels of 0.02 μg/L, 0.2 μg/L and 1.0 μg/L, the mean recoveries were from 75.8% to 110.2%, with an acceptable coefficient of variation (3.3–20%, n = 6) for water samples. The limits of the method were 3.5–9.3 ng/L for DPAs in environmental water samples, and 0.06–0.09 μg/kg for DPAs and ADPs in soil and sediment samples. For soil and sediment samples, results determined by the present IC–MS method were in good agreement with that determined by LC–MS in our previous study.
Co-reporter:Meseret Amde, Zhi-Qiang Tan, Rui Liu, Jing-Fu Liu
Journal of Chromatography A 2015 Volume 1395() pp:7-15
Publication Date(Web):22 May 2015
DOI:10.1016/j.chroma.2015.03.049
•Stable ZnO-NF was prepared in [HMIM][PF6] ionic liquid.•ZnO-NF was used in single drop microextraction of fungicides for the first time.•Introduction of ZnO NPs to [HMIM][PF6] enhanced the extraction efficiency.•The method is applicable for extraction of fungicides in environmental waters.Using a nanofluid obtained by dispersing ZnO nanoparticles (ZnO NPs) in 1-hexyl-3-methylimidazolium hexafluorophosphate, new single drop microextraction method was developed for simultaneous extraction of three fungicides (chlorothalonil, kresoxim-methyl and famoxadone) in water samples prior to their analysis by high performance liquid chromatography (HPLC-VWD). The parameters affecting the extraction efficiency such as amount of ZnO NPs in the nanofluid, solvent volume, extraction time, stirring rate, pH and ionic strength of the sample solution were optimized. Under the optimized conditions, the limits of detection were in the range of 0.13–0.19 ng/mL, the precision of the method assessed with intra-day and inter-day relative standard deviations were <4.82% and <7.04%, respectively. The proposed method was successfully applied to determine the three fungicides in real water samples including lake water, river water, as well as effluent and influent of wastewater treatment plant, with recoveries in the range of 74.94–96.11% at 5 ng/mL spiking level. Besides to being environmental friendly, the high enrichment factor and the data quality obtained with the proposed method demonstrated its potential for application in multi residue analysis of fungicides in actual water samples.
Co-reporter:Li-Jie Dong, Zhi-Qiang Tan, Ming Chen and Jing-Fu Liu
Analytical Methods 2015 vol. 7(Issue 4) pp:1380-1386
Publication Date(Web):15 Dec 2014
DOI:10.1039/C4AY02635G
Hollow fiber supported liquid membrane (HFSLM) was applied for the extraction of bisphenols (BPs), including bisphenol S, bisphenol AF, tetramethylbisphenol A, tetrachlorobisphenol A and tetrabromobisphenol A from water samples. The undecane solution of 1.0% (m/v) tri-n-octylphosphine oxide was supported on the pores of the polypropylene hollow fiber membranes (280 μm i.d., 50 μm wall thickness, 0.1 μm pore size, 60 cm length) to form a liquid membrane. The lumen of the hollow fiber membranes was then filled with 0.3 M NaOH as an acceptor to prepare the extraction device, which was placed into a 500 mL water sample (donor) adjusted to pH 4.0 with HCl. After shaking at 200 rpm for 180 min, the acceptor (∼30 μL) was collected and injected into the high performance liquid chromatography system for the determination of the BPs. The proposed HFSLM method provided good enrichment factors (1370–2138), low detection limits (0.1–0.2 μg L−1) and good repeatability (RSD = 2.6–8.8%, n = 5). The proposed method was applied to determine the five target BPs in waste water, tap water, river water and lake water samples with satisfactory spiked recoveries (68.6% to 134%) at 0.5 and 1 μg L−1 spiking levels, demonstrating the practicality of the proposed method for the determination of BPs in environmental water samples.
Co-reporter:Tesfaye Tolessa, Jingfu Liu
Trends in Environmental Analytical Chemistry 2015 Volumes 6–7() pp:10-20
Publication Date(Web):May–August 2015
DOI:10.1016/j.teac.2015.04.002
Negligible depletion micro-extraction (nd-ME) and full depletion micro-extraction (fd-ME) have been developed for specific purposes in environmental studies. Nd-ME is mainly designed to measure the free concentration and therefore evaluate the bioavailability of analytes in environmental matrices, and achieved by using large ratio of sample to extraction phase or extraction phase with low distribution coefficients for analytes. On the contrary, fd-ME is adopted to avoid matrix effects by determining the total amount of the analyte in the samples, and performed by using very low ratio of sample to extraction phase or extraction phase with extremely large distribution coefficients for analytes. In this review article, we highlight the basic concepts and applications of nd-ME and fd-ME in environmental sciences.
Co-reporter:Weidong Wang, Yongguang Yin, Zhiqiang Tan and Jingfu Liu
Nanoscale 2014 vol. 6(Issue 16) pp:9588-9593
Publication Date(Web):16 Jun 2014
DOI:10.1039/C4NR03198A
Based on the “coffee-ring effect”, we developed a highly efficient SERS platform which integrates the fabrication of SERS-active substrates and the preconcentration of analytes into one step. The high sensitivity, robustness, reproducibility and simplicity make this platform ideal for on-site analysis of small volume samples at low concentrations in complex matrices.
Co-reporter:Zhi-Qiang Tan, Jing-Fu Liu, Yong-Guang Yin, Qian-Tao Shi, Chuan-Yong Jing, and Gui-Bin Jiang
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 22) pp:19833
Publication Date(Web):October 21, 2014
DOI:10.1021/am5052069
The exposure of millions of people to unsafe levels of arsenite (AsIII) and arsenate (AsV) in drinking waters calls for the development of low-cost methods for on-site monitoring these two arsenic species in waters. Herein, for the first time, tetradecyl (trihexyl) phosphonium chloride ionic liquid was found to selectively bind with AsIII via extended X-ray absorption fine structure (EXAFS) analysis. Based on the finding, an AsIII-specific probe was developed by modifying gold nanoparticles with the ionic liquid. Futhermore, Hofmeister effect was primarily observed to significantly affect the sensitivity of gold nanoparticle probe. With the colorimetric probe, we developed a protocol for naked eye speciation test of AsIII and AsV at levels below the World Health Organization (WHO) guideline of 10 μg L–1. This method featured with high tolerance to common coexisting ions such as 10 mM PO43–, and was validated by assaying certified reference and environmental water samples.Keywords: arsenic; gold nanoparticle; Hofmeister effect; interaction; ionic liquid; visual test
Co-reporter:Zong-Mian Zhang, Jing-Fu Liu, Rui Liu, Jie-Fang Sun, and Guo-Hua Wei
Analytical Chemistry 2014 Volume 86(Issue 15) pp:7286
Publication Date(Web):June 30, 2014
DOI:10.1021/ac5017387
By coupling surface-enhanced Raman spectroscopy (SERS) with thin layer chromatography (TLC), a facile and powerful method was developed for on-site monitoring the process of chemical reactions. Samples were preseparated on a TLC plate following a common TLC procedure, and then determined by SERS after fabricating a large-area, uniform SERS substrate on the TLC plate by spraying gold nanoparticles (AuNPs). Reproducible and strong SERS signals were obtained with substrates prepared by spraying 42-nm AuNPs at a density of 5.54 × 1010 N/cm2 on the TLC plate. The capacity of this TLC-SERS method was evaluated by monitoring a typical Suzuki coupling reaction of phenylboronic acid and 2-bromopyridine as a model. Results showed that this proposed method is able to identify reaction product that is invisible to the naked eye, and distinguish the reactant 2-bromopyridine and product 2-phenylpyridine, which showed almost the same retention factors (Rf). Under the optimized conditions, the peak area of the characteristic Raman band (755 cm–1) of the product 2-phenylpyridine showed a good linear correlation with concentration in the range of 2–200 mg/L (R2 = 0.9741), the estimated detection limit (1 mg/L 2-phenylpyridine) is much lower than the concentration of the chemicals in the common organic synthesis reaction system, and the product yield determined by the proposed TLC-SERS method agreed very well with that by UPLC-MS/MS. In addition, a new byproduct in the reaction system was found and identified through continuous Raman detection from the point of sample to the solvent front. This facile TLC-SERS method is quick, easy to handle, low-cost, sensitive, and can be exploited in on-site monitoring the processes of chemical reactions, as well as environmental and biological processes.
Co-reporter:Yongguang Yin, Sujuan Yu, Jingfu Liu, and Guibin Jiang
Environmental Science & Technology 2014 Volume 48(Issue 5) pp:2671-2679
Publication Date(Web):January 29, 2014
DOI:10.1021/es404195r
Naturally occurring Au nanoparticles (AuNPs) have been widely observed in ore deposits, coal, soil, and environmental water. Identifying the source of these naturally occurring AuNPs could be helpful for not only the discovery of Au deposits through advanced exploration methods, but also the elucidation of the biogeochemical cycle and environmental toxicity of ionic Au and engineered AuNPs. Here, we investigated the effect of natural/simulated sunlight and heating on the reduction of ionic Au by ubiquitous dissolved organic matter (DOM) in river water. The reductive process probed by X-ray photoelectron spectroscopy revealed that phenolic, alcoholic, and aldehyde groups in DOM act as reductive sites. Long-time exposure with thermal and photoirradiation induced the further fusion and growth of AuNPs to branched Au nanostructure as precipitation. The formation processes and kinetics of AuNPs were further investigated using humic acid (HA) as the DOM model, with comprehensive characterizing methods. We have observed that HA can reduce ionic Au(III) complex (as chloride or hydroxyl complex) to elemental Au nanoparticles under sunlight or heating. In this process, nearly all of the Au(III) could be reduced to AuNPs, in which HA serves as not only the reductive agent, but also the coating agent to stabilize and disperse AuNPs. The size and stability of AuNPs were highly dependent on the concentration ratio of Au(III) to HA. These results imply that, besides biological processes, this thermal or photochemical reduction process is another possible source of naturally occurring AuNPs in natural environments, which possibly has critical impacts on the transport and transformation of Au and engineered AuNPs.
Co-reporter:Su-juan Yu, Yong-guang Yin, Jing-bo Chao, Mo-hai Shen, and Jing-fu Liu
Environmental Science & Technology 2014 Volume 48(Issue 1) pp:403-411
Publication Date(Web):December 11, 2013
DOI:10.1021/es404334a
The fast growing and abundant use of silver nanoparticles (AgNPs) in commercial products alerts us to be cautious of their unknown health and environmental risks. Because of the inherent redox instability of silver, AgNPs are highly dynamic in the aquatic system, and the cycle of chemical oxidation of AgNPs to release Ag+ and reconstitution to form AgNPs is expected to occur in aquatic environments. This study investigated how inevitable environmentally relevant factors like sunlight, dissolved organic matter (DOM), pH, Ca2+/Mg2+, Cl–, and S2– individually or in combination affect the chemical transformation of AgNPs. It was demonstrated that simulated sunlight induced the aggregation of AgNPs, causing particle fusion or self-assembly to form larger structures and aggregates. Meanwhile, AgNPs were significantly stabilized by DOM, indicating that AgNPs may exist as single particles and be suspended in natural water for a long time or delivered far distances. Dissolution (ion release) kinetics of AgNPs in sunlit DOM-rich water showed that dissolved Ag concentration increased gradually first and then suddenly decreased with external light irradiation, along with the regeneration of new tiny AgNPs. pH variation and addition of Ca2+ and Mg2+ within environmental levels did not affect the tendency, showing that this phenomenon was general in real aquatic systems. Given that a great number of studies have proven the toxicity of dissolved Ag (commonly regarded as the source of AgNP toxicity) to many aquatic organisms, our finding that the effect of DOM and sunlight on AgNP dissolution can regulate AgNP toxicity under these conditions is important. The fact that the release of Ag+ and regeneration of AgNPs could both happen in sunlit DOM-rich water implies that previous results of toxicity studies gained by focusing on the original nature of AgNPs should be reconsidered and highlights the necessity to monitor the fate and toxicity of AgNPs under more environmentally relevant conditions.
Co-reporter:Yumin Niu, Jingfu Liu, Yong Liang, Zhineng Hao, Jiyan Liu, Yuchen Liu, and Xue Sun
Environmental Science & Technology 2014 Volume 48(Issue 6) pp:3336-3343
Publication Date(Web):February 21, 2014
DOI:10.1021/es500200p
Aluminum dialkyl phosphinates (ADPs) are emerging phosphorus flame retardants due to their superior characteristics, but their analytical method, and occurrence and fate in environments have never been reported. For the first time, we developed a method for the analysis of trace ADPs and their hydrolysates (dialkyl phosphinic acids, DPAs), and studied their occurrences and fates in soils and sediments. We found that ADPs are hardly dissolved in water and organic solvents, but are dissolved and hydrolyzed to DPAs in 30 mM NH3·H2O, thus both ADPs and DPAs can be determined by liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) in the form of DPAs. ADPs and DPAs in soil and sediment samples were determined by (i) extracting both ADPs and DPAs with 75 mM NH3·H2O, and selectively extract DPAs only with formic acid–water–methanol (5:5:90, v/v/v); (ii) quantifying the total content of ADPs and DPAs, and DPAs by LC-MS/MS analysis of the DPA contents in the former and the latter extract, respectively; and (iii) calculating ADPs from the content difference between the former and the latter extracts. The limit of quantifications (LOQs) of the proposed method were 0.9–1.0 μg/kg, and the mean recoveries ranged from 69.0% to 112.4% with relative standard deviations ≤21% (n = 6). In soil and sediment samples around a manufacturing plant, ADPs and DPAs were detected in surface soils in the ranges of 3.9–1279.3 and 1.0–448.6 μg/kg, respectively. While ADPs were found in all the samples of the soil and sediment cores from the drain outlet and the waste residue treatment site at levels ranging from 30.8 to 4628.0 μg/kg, DPAs were found in more than 90% of these samples with concentrations in the range of 1.1–374.6 μg/kg. The occurrences of ADPs and DPAs are not in correlation with the total organic carbon, whereas the occurrences of DPAs are highly correlated with the sample pH. Our study also suggests that the DPAs in the samples sourced from the hydrolysis of ADPs. The high hydrolysis degrees of ADPs (up to 49.6%) suggest that once released into the environment, ADPs are likely to coexist with their hydrolysates. Thus, to evaluate the environmental safety of ADPs, the environmental behavior and toxicity of both ADPs and DPAs should be considered.
Co-reporter:Yongguang Yin, Mohai Shen, Xiaoxia Zhou, Sujuan Yu, Jingbo Chao, Jingfu Liu, and Guibin Jiang
Environmental Science & Technology 2014 Volume 48(Issue 16) pp:9366-9373
Publication Date(Web):July 22, 2014
DOI:10.1021/es502025e
Photoinduced reduction of silver ion (Ag+) to silver nanoparticles (AgNPs) by dissolved organic matter (DOM) plays a crucial role in the transformation and transport of engineered AgNPs and Ag+ in aquatic environments. DOM is a mixture of natural polymers with wide molecular weight (MW) distribution, and the roles of specific components of DOM in the photoreduction of Ag+ to AgNPs are still not understood. In this study, MW fractionated natural organic matter (Mf-NOM) were investigated for their roles on the photoreduction process and stabilization of the formed AgNPs. This photoinduced reduction process depends highly on pH, concentration of Ag+ and NOM, light quality, and the MW of Mf-NOM. Monochromatic radiation and light attenuation correction suggested that the difference of Mf-NOM on reduction was mainly ascribed to the differential light attenuation of Mf-NOM rather than the “real” reductive ability. More importantly, compared with low MW fractions, the high MW Mf-NOMs exhibit drastically higher capability in stabilizing the photosynthesized AgNPs against Ca2+-induced aggregation. This finding is important for a better understanding of the differential roles of Mf-NOM in the transformation and transport of Ag+ and engineered AgNPs in DOM-rich surface water.
Co-reporter:Xiao-Xia Zhou, Rui Liu, and Jing-Fu Liu
Environmental Science & Technology 2014 Volume 48(Issue 24) pp:14516
Publication Date(Web):November 22, 2014
DOI:10.1021/es504088e
Sensitive and rapid methods for speciation analysis of nanoparticulate Ag (NAg) and Ag(I) in complex matrices are urgently needed for understanding the environmental effects and biological toxicity of silver nanoparticles (AgNPs). Herein we report the development of a universal liquid chromatography (LC) method for rapid and high resolution separation of dissoluble Ag(I) from nanoparticles covering the entire range of 1–100 nm in 5 min. By using a 500 Å poresize amino column, and an aqueous mobile phase containing 0.1% (v/v) FL-70 (a surfactant) and 2 mM Na2S2O3 at a flow rate of 0.7 mL/min, all the nanoparticles of various species such as Ag and Ag2S were eluted in one fraction, while dissoluble Ag(I) was eluted as a baseline separated peak. The dissoluble Ag(I) was quantified by the online coupled ICP-MS with a detection limit of 0.019 μg/L. The NAg was quantified by subtracting the dissoluble Ag(I) from the total Ag content, which was determined by ICP-MS after digestion of the sample without LC separation. While the addition of FL-70 and Na2S2O3 into the mobile phase is essential to elute NAg and Ag(I) from the column, the use of 500 Å poresize column is the key to baseline separation of Ag(I) from ∼1 nm AgNPs. The feasibility of the proposed method was demonstrated in speciation analysis of dissoluble Ag(I) and NAg in antibacterial products and environmental waters, with very good chromatographic repeatability (relative standard deviations) in both peak area (<2%) and retention time (<0.6%), excellent spiked recoveries in the range of 84.7–102.7% for Ag(I) and 81.3–106.3% for NAg. Our work offers a novel approach to rapid and baseline separation of dissoluble metal ions from their nanoparticulate counterparts covering the whole range of 1–100 nm.
Co-reporter:Yared Merdassa, Jing-fu Liu and Negussie Megersa
Analytical Methods 2014 vol. 6(Issue 9) pp:3025-3033
Publication Date(Web):03 Feb 2014
DOI:10.1039/C4AY00022F
A one-step microwave-assisted extraction (MAE) procedure for highly efficient multiresidue extraction of seven fungicides (cymoxanil, metalaxyl, mandipropamid, folpet, chlorothalonil, kresoxim-methyl and famoxadone) in soil was developed. The trace residue levels in the soil were determined by high performance liquid chromatography (HPLC) with variable wavelength detection (VWD). Parameters affecting the MAE process such as the type and volume of the extraction solvent, irradiation power, temperature, irradiation time, moisture and salt addition were optimized. Under the optimal conditions, extraction efficiencies in the range of 72.4–99.4% were obtained for all the fungicides studied. The method was linear over the range of 0.01–10 μg g−1 with correlation coefficients (r2) between 0.9989 and 0.9999. LODs (S/N = 3) and LOQs (S/N = 10) obtained varied from 0.0006 to 0.0015 μg g−1 and from 0.002 to 0.005 μg g−1, respectively. The proposed method has been successfully applied to the analysis of real soil samples and acceptable recoveries from 57.5 to 122% with RSDs ≤14% were obtained. The overall results have been compared with Soxhlet, shake-flask and ultrasonic solvent extraction techniques. Thus, the developed method could be efficiently used for selective extraction and determination of the target analytes from complex soil matrices.
Co-reporter:Xu Ma, Yong-guang Yin, Jian-bo Shi, Jing-fu Liu and Gui-bin Jiang
Analytical Methods 2014 vol. 6(Issue 1) pp:164-169
Publication Date(Web):29 Oct 2013
DOI:10.1039/C3AY41625A
Species-specific isotope dilution (SSID) in combination with gas chromatography-inductively coupled plasma-mass spectrometry (GC-ICP-MS) has been developed for the separation and determination of methylmercury (MeHg) in water, sediments and biological tissues. Optimum conditions for the measurement of isotope ratios on the transient chromatographic peaks have been established. SSID analysis was performed using a laboratory synthesized enriched spike of Me198Hg. Isotope ratio precision based on the peak area measurements was 1.4% RSD for 50 pg (as Hg). The absolute detection limits obtained with GC-ICP-MS were 4.3 pg for 198Hg and 8.1 pg for 202Hg, respectively. Analytical precision was typically less than 3.6% RSD over eight repeated measurements. The accuracy of the method has been compared with the method with Tl as internal standard and further validated with certified reference materials (ERM-cc580 for sediments and Tort-2 for the biological tissues). The results obtained by SSID-GC-ICP-MS were in good agreement with the certified reference values.
Co-reporter:Rui Liu, Jing-Fu Liu, Zong-Mian Zhang, Li-Qiang Zhang, Jie-Fang Sun, Meng-Tao Sun, and Gui-Bin Jiang
The Journal of Physical Chemistry Letters 2014 Volume 5(Issue 6) pp:969-975
Publication Date(Web):February 27, 2014
DOI:10.1021/jz500238z
For their unique properties, core–shell bimetal nanostructures are currently of immense interest. However, their synthesis is not a trivial work, and most works have been conducted on nanoparticles. We report herein a new synthetic tactic for submonolyer-Pt coated ultrathin Au nanowires (NWs). Besides providing a strong electromagnetic field for Raman signal enhancing, the underlined Au NWs markedly enhanced the catalytic activity of Pt atoms through increasing their dispersity and altering their electronic state. The integration of excellent SERS and high catalytic activity within Au@Pt NWs enable it work as platform for catalyzed reaction study. As a proof of principle, the self-organized Au@Pt NWs thin film is employed in operando SERS monitoring of the p-nitrothiophenol reduction process. In addition to providing kinetic data for structure–activity relationship study, the azo-intermidate independent path is also directly witnessed. This synthetic tactic can be extended to other metals, thus offering a general approach to modulate the physical/chemical properties of both core and shell metals.Keywords: atomically dispersed catalyst; bimetal nanocatalyst; core−shell nanowires; formic acid electrooxidation; reaction mechanism; surface enhanced Raman scattering;
Co-reporter:Zhen Zhang, Jing-fu Liu, Ting-ting Feng, Yan Yao, Li-hong Gao, and Gui-bin Jiang
Environmental Science & Technology 2013 Volume 47(Issue 1) pp:454
Publication Date(Web):December 7, 2012
DOI:10.1021/es303858a
Due to the widespread occurrence in the environment and potential risk toward organisms of fluoroquinolones (FQs), it is of importance to develop high efficient methods for assessing their occurrence and environmental risk. A monoclonal antibody (Mab) with broad cross-reactivity to FQs was produced by immunizing BALB/c mice with a synthesized immunogen prepared by conjugating ciprofloxacin with bovine serum albumin. This developed Mab (C2F3C2) showed broad and high cross-reactivity (40.3–116%) to 12 out of the 13 studied FQs. Using this Mab and norfloxacin conjugated with carrier protein ovalbumin as coating antigen, a time-resolved fluoroimmunoassay (TRFIA) method was developed for determining the total concentration of at least 12 FQs in environmental waters. The respective detection limit (LOD) and IC50 calculated from the standard curve were 0.053 μg/L and 1.83 μg/L for enrofloxacin (ENR). The LODs of the other FQs, estimated based on the corresponding cross-reactivity and the LOD of ENR, were in the range of 0.051–0.10 μg/L. The developed TRFIA method showed good tolerance to various interfering substances present in environmental matrix at relevant levels, such as humic acids (0–10 mg/L DOC), water hardness (0–2% Ca2+ and Mg2+, w/v), and heavy metals (0–1 mg/L). The spiked recoveries estimated by spiking 0.5, 1, and 2 μg/L of five representative FQs into various water samples including paddy water, tap water, pond water, and river water were in the range of 63–120%. The measured total FQ concentration by TRFIA agreed well with that of liquid chromatography–tandem mass spectrometry and was applied to directly evaluate the occurrence and environmental risk of FQs in the surface water of a case area. TRFIA showed high efficiency and great potential in environmental risk assessment as it measures directly the total concentration of a class of pollutants.
Co-reporter:Su-juan Yu, Jing-bo Chao, Jia Sun, Yong-guang Yin, Jing-fu Liu, and Gui-bin Jiang
Environmental Science & Technology 2013 Volume 47(Issue 7) pp:3268
Publication Date(Web):March 4, 2013
DOI:10.1021/es304346p
The toxic mechanism of silver nanoparticles (AgNPs) is still debating, partially because of the common co-occurrence and the lack of methods for separation of AgNPs and Ag+ in biological matrices. For the first time, Triton-X 114-based cloud point extraction (CPE) was proposed to separate AgNPs and Ag+ in the cell lysates of exposed HepG2 cells. Cell lysates were subjected to CPE after adding Na2S2O3, which facilitated the transfer of AgNPs into the nether Triton X-114-rich phase by salt effect and the preserve of Ag+ in the upper aqueous phase through the formation of hydrophilic complex. Then the AgNP and Ag+ contents in the exposed cells were determined by ICP-MS after microwave digestion of the two phases, respectively. Under the optimized conditions, over 67% of AgNPs in cell lysates were extracted into the Triton X-114-rich phase while 94% of Ag+ remained in the aqueous phase, and the limits of detection for AgNPs and Ag+ were 2.94 μg/L and 2.40 μg/L, respectively. This developed analytical method was applied to quantify the uptake of AgNPs to the HepG2 cells. After exposure to 10 mg/L AgNPs for 24 h, about 67.8 ng Ag were assimilated per 104 cells, in which about 10.3% silver existed as Ag+. Compared to the pristine AgNPs (with 5.2% Ag+) for exposure, the higher ratio of Ag+ to AgNPs in the exposed cells (10.3% Ag+) suggests the transformation of AgNPs into Ag+ in the cells and/or the higher uptake rate of Ag+ than that of AgNPs. Given that the toxicity of Ag+ is much higher than that of AgNPs, the substantial content of Ag+ in the exposed cells suggests that the contribution of Ag+ should be taken into account in evaluating the toxicity of AgNPs to organisms, and previous results obtained by regarding the total Ag content in organisms as AgNPs should be reconsidered.
Co-reporter:Ying-Di Feng, Zhi-Qiang Tan, Xiao-Wei Wang and Jing-Fu Liu
Analytical Methods 2013 vol. 5(Issue 4) pp:904-909
Publication Date(Web):30 Nov 2012
DOI:10.1039/C2AY26216A
Hollow fiber supported liquid membrane (HFSLM) extraction often suffers from matrix effects in extracting weak organic acids in environmental waters, but the reasons for which are unclear. This work systematically studied the influence of dissolved carbon dioxide and carbonate on the HFSLM extraction of analytes in environmental waters, by using triclosan and its two typical degradation products, 2,4-dichlorophenol and 2,4,6-trichlorophenol, as model compounds. HFSLM was conducted by immersing a HFSLM extraction device into a 200 mL water sample modified with 0.01 M HCl and 10% (m/v) NaCl, and shaking at 250 rpm for 90 min. The extraction device was prepared by immobilizing dihexyl ether on the polypropylene hollow fiber membrane wall (60 cm length, 50 μm wall thickness, 280 μm inner diameter), filling the fiber lumen with 0.4 M NaOH as acceptor, and closing the two ends of the fiber with aluminum foil. It was demonstrated that the dissolved carbon dioxide and carbonate present in environmental samples reduces the acceptor pH and thus the recovery of target analytes, and purging the acidified sample with ∼50 mL min−1 N2 for 15 min is a very efficient approach to eliminate this matrix effect. With this purging pretreatment, the recoveries of the analytes in environmental samples increased substantially from below 40% to between 63% and 121%. For the three analytes, the proposed HFSLM method provided enrichment factors in the range of 1090–1322, and detection limits in the range of 0.1–0.2 μg L−1 by coupling with an ultra-performance liquid chromatography-mass spectrometry system.
Co-reporter:Yared Merdassa, Jing-fu Liu, Negussie Megersa
Talanta 2013 Volume 114() pp:227-234
Publication Date(Web):30 September 2013
DOI:10.1016/j.talanta.2013.04.035
•One-step MAE procedure was developed for simultaneous extraction of organophosphorus pesticides and fungicides in soils.•Over 96% analytes in soils were extracted in 10 min with only 12 mL hexane–acetone (2:1, v/v).•The analytes in extracts were analyzed directly by GC–MS without any further cleanup.•High spiked recoveries (71.5−98.1%) and low detection limits (0.10−0.12 ng g−1) were obtained.A one-step microwave-assisted extraction (MAE) procedure was developed for the simultaneous extraction of organophosphorus pesticide and fungicide residues in soil which have been greatly used in agriculture. Parameters that could influence the MAE efficiency such as irradiation power, temperature, time and solvent were investigated, and extraction efficiencies in the range of 92.6−103.7% were obtained using 400 W (100% output) at 160 °C for 10 min with only 12 mL of acetone–hexane (2:1, v/v). The analytes in extracts were analyzed directly by gas chromatography–mass spectrometry (GC–MS) without any further cleanup. At 5 and 50 ng g−1 fortification levels for each analyte, the average recoveries obtained were ranged from 70.0% to 120.0% with relative standard deviation (RSD) between 0.2% and 14%. The method was linear over 1–250 ng g−1 with a correlation coefficient (r2) between 0.9916 and 0.9966. The detection limits (S/N=3) were between 0.10 and 0.12 ng g−1. The applicability of the method was demonstrated by analyzing field soil samples collected from six intensive horticultural sites in Ethiopia.
Co-reporter:YongGuang Yin;JingFu Liu;GuiBin Jiang
Science Bulletin 2013 Volume 58( Issue 2) pp:150-161
Publication Date(Web):2013 January
DOI:10.1007/s11434-012-5497-0
Mercury (Hg), arsenic (As) and selenium (Se) are ubiquitous in the environment and exist in a variety of species, which have great influence on their transport, bioaccumulation and toxicity. This review presents the recent research progress in speciation analysis of Hg, As, and Se, with emphasis on enhanced cold vapor generation as interface for liquid chromatography and atomic spectrometry, speciation of volatile species in gas phase, and isotope dilution technique to improve the precision and accuracy of speciation. Hyphenated techniques to characterize the complexes of Hg and As with phytochelatins and chromatographic separation coupled with multi-collector-inductively coupled plasma mass spectrometry to measure species-specific isotopic ratios, are also briefly discussed.
Co-reporter:Su-juan Yu, Yong-guang Yin and Jing-fu Liu
Environmental Science: Nano 2013 vol. 15(Issue 1) pp:78-92
Publication Date(Web):06 Dec 2012
DOI:10.1039/C2EM30595J
Silver nanoparticles (AgNPs) are well known for their excellent antibacterial ability and superior physical properties, and are widely used in a growing number of applications ranging from home disinfectants and medical devices to water purificants. However, with the accelerating production and introduction of AgNPs into commercial products, there is likelihood of release into the environment, which raises health and environmental concerns. This article provides a critical review of the state-of-knowledge about AgNPs, involving the history, analysis, source, fate and transport, and potential risks of AgNPs. Although great efforts have been made in each of these aspects, there are still many questions to be answered to reach a comprehensive understanding of the positive and negative effects of AgNPs. In order to fully investigate the fate and transport of AgNPs in the environment, appropriate methods for the preconcentration, separation and speciation of AgNPs should be developed, and analytical tools for the characterization and detection of AgNPs in complicated environmental samples are also urgently needed. To elucidate the environmental transformation of AgNPs, the behavior of AgNPs should be thoroughly monitored in complex environmental relevant conditions. Furthermore, additional in vivo toxicity studies should be carried out to understand the exact toxicity mechanism of AgNPs, and to predict the health effects to humans.
Co-reporter:Zhi-qiang Tan, Jing-fu Liu and Gui-bin Jiang
Nanoscale 2012 vol. 4(Issue 21) pp:6735-6738
Publication Date(Web):24 Aug 2012
DOI:10.1039/C2NR31753B
By combining Fe3O4 magnetic nanoparticle-based solid phase extraction with a gold nanoparticle-based visual test, a novel method was developed for the field assay of Cu(II) in environmental water at subparts per billion-levels within 30 min. When a 200 mL water sample was treated with 12.5 mg L−1 Fe3O4 nanoparticles by the proposed procedure, the detection limit with the naked eye was 0.2 μg L−1 Cu(II). The proposed method is very specific to Cu(II), with tolerance against at least 100-fold amounts of other environmentally relevant metal ions except for Hg(II) (25-fold), and was successfully applied to the detection of trace Cu(II) in tap water, river water, and treated wastewater, and results agreed well with that determined by inductively coupled plasma-mass spectrometry (ICP-MS).
Co-reporter:Yongguang Yin, Yi Liu, Jingfu Liu, Bin He and Guibin Jiang
Analytical Methods 2012 vol. 4(Issue 4) pp:1122-1125
Publication Date(Web):07 Mar 2012
DOI:10.1039/C2AY05886C
Volatile species generation-flameless/flame atomization-atomic fluorescence spectrometry (VSG-FL/FA-AFS) without chromatographic separation was developed for quantitative determination of inorganic mercury (IHg) and methylmercury (MeHg) in water and biological samples by using a commercially available atomic fluorescence spectrometer. In the proposed method, inorganic mercury was measured by using the flameless mode. However, by using the flame atomization mode, the volatile hydride of MeHg generated by KBH4 can be transformed to elemental mercury vapour in the reductive argon–hydrogen flame, and both MeHg and IHg give a fluorescence signal in this flame atomization mode. Then, the concentration of MeHg can be calculated by subtracting IHg concentration from the total mercury concentration. The limits of detection for IHg and MeHg were 0.03 μg L−1 and 0.05 μg L−1, respectively. Spiked environmental water samples including seawater, tap water and river water were determined and satisfactory recoveries were obtained for MeHg and IHg. Furthermore, the proposed method was successfully applied to analyze biological certified reference material, TORT-2 (lobster hepatopancreas).
Co-reporter:Yongguang Yin, Jingfu Liu, and Guibin Jiang
ACS Nano 2012 Volume 6(Issue 9) pp:7910
Publication Date(Web):July 22, 2012
DOI:10.1021/nn302293r
Despite the possible occurrence of metal nanoparticles in the environment due to the discharge of engineered nanoparticles and the natural transformation of metal ions into metal nanoparticles, little is known about the transformation mechanism, fates, behaviors, and effects of these nanoparticles in the environment. Here, we show that dissolved organic matter (DOM) in environmental waters can mediate the reduction of ionic Ag and Au to their metallic nanoparticles under natural sunlight, suggesting that this process may be general for metals with high reduction potential. We demonstrated that the reduction was mediated by superoxide from photoirradiation of the phenol group in DOM, and the dissolved O2 significantly enhanced the formation of Ag nanoparticles. These results imply that previous knowledge about O2-induced dissolution and its effect on persistence of Ag nanoparticles should be reconsidered in a sunlit DOM-rich aqueous environment. This study can also shed light on understanding possible natural sources of Ag and Au nanoparticles in the aquatic environment, which is possibly critical in the supergene enrichment of Ag and Au.Keywords: dissolved organic matter; gold nanoparticles; naturally occurring nanoparticles; reduction; silver nanoparticles; superoxide
Co-reporter:Zhi-qiang Tan, Jing-fu Liu, Long Pang
TrAC Trends in Analytical Chemistry 2012 Volume 39() pp:218-227
Publication Date(Web):October 2012
DOI:10.1016/j.trac.2012.06.005
Ionic liquids (ILs) are regarded as non-molecular solvents, as they are composed entirely of cations and anions. ILs possess several excellent unique properties (e.g., low volatility, high thermal stability, specific electrochemical characteristics, easy design, tunable viscosity, and miscibility with water or organic solvents). These properties make ILs attractive candidates for various analytical applications, the number of publications on which has increased exponentially in the past decade.This article presents an overview of representative applications of ILs in advances in analytical chemistry that benefited from the unique properties of ILs, including the development achieved by using ILs as extraction solvents, dissolution solvents and separation media.Highlights► Unique properties make ionic liquids (ILs) attractive for analytical applications. ► Analytical chemistry has benefited from the unique properties of ionic liquids (ILs). ► Challenges and perspectives of applying ionic liquids (ILs) in analytical chemistry.
Co-reporter:Jing-fu Liu, Su-juan Yu, Yong-guang Yin, Jing-bo Chao
TrAC Trends in Analytical Chemistry 2012 Volume 33() pp:95-106
Publication Date(Web):March 2012
DOI:10.1016/j.trac.2011.10.010
There is a growing production and application of silver nanoparticles (AgNPs) (e.g., in cosmetics products, food technology, textiles and fabrics, and medical products and devices). The rapid growth in the commercial use of AgNPs will inevitably increase exposure to silver in the environment and among the general population.Compared to the vast application of silver, information on the fate, the transformation and the toxicity of AgNPs is very limited. Lack of proper techniques to trace AgNPs in complex matrixes hinders investigation. Thus, development of methods for analysis of AgNPs is very important to achieve detailed insights into the fate, the transport and exposure of AgNPs in environment.This review presents state-of-the-art methods for separation, identification, characterization and quantification of AgNPs. We also discuss perspectives on future developments.Highlights► Production and application of silver nanoparticles will increase exposure to silver. ► Developing analytical methods for silver nanoparticles is of great importance. ► Separating, identifying, characterizing and quantifying silver nanoparticles.
Co-reporter:Long Pang, Jing-Fu Liu
Journal of Chromatography A 2012 1230() pp: 8-14
Publication Date(Web):
DOI:10.1016/j.chroma.2012.01.052
Co-reporter:Rui Liu, Jing-fu Liu, Su-juan Yu, Qian Liu and Gui-bin Jiang
Chemical Communications 2011 vol. 47(Issue 5) pp:1613-1615
Publication Date(Web):26 Nov 2010
DOI:10.1039/C0CC04490C
Ultrafine ligament noble metal nanoporous films are successfully fabricated by self-organization of ultrathin nanowires. The replacement of weak binding capping agent Triton X-114, used for stabilizing nanowires, by Cl− is claimed for this self-organization. Our method is also applicable for synthesizing other hierarchical nanostructure-like hybrid nanoporous films.
Co-reporter:Jing-bo Chao, Jing-fu Liu, Su-juan Yu, Ying-di Feng, Zhi-qiang Tan, Rui Liu, and Yong-guang Yin
Analytical Chemistry 2011 Volume 83(Issue 17) pp:6875
Publication Date(Web):July 28, 2011
DOI:10.1021/ac201086a
The rapid growth in commercial use of silver nanoparticles (AgNPs) will inevitably increase silver exposure in the environment and the general population. As the fate and toxic effects of AgNPs is related to the Ag+ released from AgNPs and the transformation of Ag+ into AgNPs, it is of great importance to develop methods for speciation analysis of AgNPs and Ag+. This study reports the use of Triton X-114-based cloud point extraction as an efficient separation approach for the speciation analysis of AgNPs and Ag+ in antibacterial products and environmental waters. AgNPs were quantified by determining the Ag content in the Triton X-114-rich phase with inductively coupled plasma mass spectrometry (ICPMS) after microwave digestion. The concentration of total Ag+, which consists of the AgNP adsorbed, the matrix associated, and the freely dissolved, was obtained by subtracting the AgNP content from the total silver content that was determined by ICPMS after digestion. The limits of quantification (S/N = 10) for antibacterial products were 0.4 μg/kg and 0.2 μg/kg for AgNPs and total silver, respectively. The reliable quantification limit was 3 μg/kg for total Ag+. The presence of Ag+ at concentrations up to 2-fold that of AgNPs caused no effects on the determination of AgNPs. In the cloud point extraction of AgNPs in antibacterial products, the spiked recoveries of AgNPs were in the range of 71.7–103% while the extraction efficiencies of Ag+ were in the range of 1.2–10%. The possible coextracted other silver containing nanoparticles in the cloud point extraction of AgNPs were distinguished by transmission electron microscopy (TEM), scanning electron microscopy (SEM)- energy dispersive spectroscopy (EDS), and UV–vis spectrum. Real sample analysis indicated that even though the manufacturers claimed nanosilver products, AgNPs were detected only in three of the six tested antibacterial products.
Co-reporter:Rui Liu, Jing-fu Liu, Xiao-xia Zhou, Meng-Tao Sun, and Gui-bin Jiang
Analytical Chemistry 2011 Volume 83(Issue 23) pp:9131
Publication Date(Web):October 21, 2011
DOI:10.1021/ac2022647
Due to its demonstrated usefulness in fields such as trace analysis, biodiagnosis, and in vivo study, surface-enhanced Raman scattering (SERS) has received renewed interest in recent years. Development of SERS substrates is of great importance as the SERS intensity and reproducibility depend strongly on the SERS substrates. In this paper we report the fabrication of Au nanoporous film (NPFs) by self-organization of networked ultrathin Au nanowires for use as SERS substrates. The acquired Au NPFs display controllable thickness, low relative density, and considerable specific surface area. Furthermore, this self-organization of nanowires not only provides abundant junctions between nanowires, 5–20 nm nanopores, and three-dimensional nanowells, but also makes nanopores/nanogaps down to 1–2 nm. These nanoscale characteristics result in a high spatial density of hotspots with Raman enhancement factors up to 109. Combined with the uniformity and high purity, our Au NPF provides high-quality substrates for SERS sensing.
Co-reporter:Rui Liu, Jing-fu Liu, Xiao-xia Zhou, and Gui-bin Jiang
Analytical Chemistry 2011 Volume 83(Issue 10) pp:3668
Publication Date(Web):April 4, 2011
DOI:10.1021/ac103222p
Au nanoporous films (NPFs) with different surface modification and morphology were fabricated and utilized as substrates for the analysis of a series of compounds, including amino acids, drug, cyclodextrins, peptides, and polyethylene glycols, using surface-assisted laser desorption/ionization time-of-flight mass spectrometry (SALDI-TOF MS). It was found that the size and interconnection state of the NPF ligament as well as the surface modification are key parameters that affect the laser desorption/ionization performance. Compared with 2,5-dihydroxybenzoic acid, pristine NPF, and aminobenzenethiol or 3-mercaptopropanoic acid modified Au NPFs, cysteine modified Au NPF generated intense and background-suppressing mass spectra. Regarding the effect of Au NPF morphology, the Au NPF with nanopores in the range of 10–30 nm, ligament size of 5 nm, and electrochemistry surface area of 26.1 m2/g exhibited the highest performance as a substrate. This high-performance NPFs can be easily fabricated by capping agent replacement induced self-organization of ultrathin nanowires, followed by self-assembling of a monolayer (SAM) of cysteine. The good thermal/electroconductivity and uniformity of Au NPFs avoided the fragmentation of analytes, eliminated the intrinsic matrix ions interference, and provided good reproducibility (RSD ≤ 10%). Additionally, the fabricated NPFs can be easy divided into microarrys (a ∼4 × 4 array from a 1 cm × 1 cm NPF). This work provides a simple and cost-effective route for acquiring an Au nanostructure as a SALDI substrate, which offers a new technique for high-speed analysis of low-molecular weight compounds.
Co-reporter:Zhen Zhang, Jing-fu Liu, Xiao-qiang Cai, Wei-wei Jiang, Wen-ru Luo, and Gui-bin Jiang
Environmental Science & Technology 2011 Volume 45(Issue 4) pp:1688-1694
Publication Date(Web):January 14, 2011
DOI:10.1021/es103514s
Two typical ionic liquids (ILs), 1-butyl-3-methylimidazolium chloride ([C4MIM]Cl) and 1-octyl-3-methylimidazolium chloride ([C8MIM]Cl), are demonstrated to associate strongly with dissolved organic matter (DOM) with distribution coefficients (KDOC) in the range of 104.2 to 104.6 for Aldrich humic acid (used as model DOM). With the increase of humic acid concentration to 11 μg/mL DOC (dissolved organic carbon), the free fraction (ratio of freely dissolved to total concentration) of [C4MIM]Cl and [C8MIM]Cl reduced to about 0.85 and 0.79, respectively. This reduction of freely dissolved concentration gave rise to remarkable reduction of bioavailability and toxicity of the two ILs. MTT assay with HepG2 cell lines showed that the EC50 values were 459 μmol/L for [C4MIM]Cl and 12 μmol/L for [C8MIM]Cl, respectively, and the cell viability increased about 50% in the presence of trace amount of humic acid (1 μg/mL DOC). The SOS/umu test indicated mutagenicity for [C4MIM]Cl at levels above 664 μmol/L, and the genotoxicity was diminished with the addition of trace humic acid (0.00000374−0.374 μg/mL DOC). The studied ILs showed acute toxicity toward model fish medaka with a 96 h median lethal concentration (LC50) of 2254 μmol/L for [C4MIM]Cl and 366 μmol/L for [C8MIM]Cl. The addition of humic acid (5.49 μg/mL DOC for [C8MIM]Cl, 1.37 μg/mL DOC for [C4MIM]Cl) to IL solutions reduced the death rate of medaka to a minimum value of ∼25% of that at zero DOC. Our results suggest that DOM may play an important role in determining the environmental fate and toxicity of imidazolium-based ILs, and its effects should be taken into account in assessing the environmental risk of ILs.
Co-reporter:Xiao-wei Wang, Jing-fu Liu, Yong-guang Yin
Journal of Chromatography A 2011 Volume 1218(Issue 38) pp:6705-6711
Publication Date(Web):23 September 2011
DOI:10.1016/j.chroma.2011.07.067
Widely used as flame retardants, organophosphate esters (OPEs) are now broadly present in the indoor and outdoor environments. Currently available liquid chromatography–tandem mass spectrometry (LC–MS/MS) methods share some drawbacks with gas chromatography (GC) methods, including time consuming, limited target OPEs, incomplete separation capability for some OPEs and low throughput. In this study, a fast and high throughput LC–MS/MS method was developed. For the first time, all the twelve OPEs that have been studied in literature, ranging from the very polar and volatile trimethyl phosphate to the very hydrophobic and non-volatile tris(2-ethylhexyl) phosphate, were separated within 11 min. Different from previous studies, we found that the blank contamination was mainly from organic mobile phase rather than the enrichment process, and it can be efficiently eliminated by using acetonitrile rather than methanol as the organic phase of the mobile phase. The signal to noise ratio (S/N) was significantly improved by using 0.1% formic acid as an organic modifier. The method exhibited high throughput and sensitivity and can baseline separate 11 of the 12 OPEs studied within 11 min with LOQs ranging from 2 to 6 ng/L. The relative standard deviations were in the range of 2–10%. For both reagent water and river water, the spiked recoveries of OPEs ranged from 70 to 110%, except for the very polar and volatile trimethyl phosphate that has recovery below 10%. The developed procedure was successfully applied to study the OPE contamination of the Songhua River, and it was found that all the target OPEs were detected with total concentrations of around 1 μg/L in the river waters.
Co-reporter:Ying-Di Feng;Zhi-Qiang Tan
Journal of Separation Science 2011 Volume 34( Issue 8) pp:965-970
Publication Date(Web):
DOI:10.1002/jssc.201000775
Abstract
A static and exhaustive extraction mode of hollow fiber-supported liquid membrane was developed for field sample passive pretreatment of environmental water samples. The extraction device was prepared by immobilizing dihexyl ether in the wall of a polypropylene hollow fiber membrane (60 cm length, 50 μm wall thickness, and 280 μm id) as liquid membrane and filling the fiber lumen with 0.1 M NaOH as acceptor, and closing the two ends of the fiber with an aluminum foil. Passive extraction was conducted by immersing the device into 15 mL water samples modified with 0.01 M HCl and 20% m/v NaCl. Model analytes including 4-chlorophenol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol were transferred into acceptor with extraction efficiencies over 79% in 10 h at room temperature, and determined by high-performance liquid chromatography. The proposed method has the enrichment factor of 394–498 and LOD of 0.3–0.4 μg/L for the three chlorophenols. Humic acid and salinity in the environmentally relevant range had no significant influence on the extraction, and chlorophenols in various environmental waters were determined with spike recoveries between 71.6 and 120%. The static passive extraction nature benefited field sample pretreatment without power, whereas the exhaustive extraction mode effectively eliminated the sample matrix effects.
Co-reporter:Jing-Fu Liu, Yong Tao, Jia Sun and Gui-Bin Jiang
Analytical Methods 2011 vol. 3(Issue 3) pp:696-702
Publication Date(Web):15 Feb 2011
DOI:10.1039/C0AY00670J
A new passive sampling device was developed for field equilibrium sampling of geosmin (GSM) and 2-methylisoborneol (MIB) in surface water. The sampling device was prepared by coating a 50 cm length polypropylene hollow fiber tubing (50 μm wall thickness, 280 μm inner diameter) with polypropylene glycol 4000. The sampler was brought into equilibrium with the sample in the field, and then transferred and immersed into 100 μL of methanol held in a little desorption device for room temperature desorption and preservation of the sampled analytes. After being transported to the laboratory, the analytes were determined by headspace solid-phase microextraction-GC-MS. The large surface area-to-volume ratio of the developed sampler facilitated the reaching of sampling equilibrium in 1 h, while the equilibrium sampling minimized the effects of environmentally relevant sampling conditions. Variation of sample pH (4.0–9.0) and salinity (0–100 mM NaCl) had no significant effects on the distribution coefficients of analytes to the sampler. The desorption device, constructed with a 200 μL glass insert, and a 2 mL brown glass vial with PTFE sealed screw cap, has no loss of analytes during the storage of the sampler. The proposed procedure had detection limits of 4 and 9 ng L−1 for GSM and MIB, respectively. This developed sampler was successfully applied to field sampling in Taihu Lake (China), with MIB and GSM detected in the range of 0.11–0.61 μg L−1 during a medium out-break of blue–green algae bloom.
Co-reporter:Zhen Zhang;JingFu Liu;Yan Yao;GuiBin Jiang
Science Bulletin 2011 Volume 56( Issue 15) pp:
Publication Date(Web):2011 May
DOI:10.1007/s11434-011-4412-4
A novel dual-label time-resolved fluoroimmunoassay method was developed for the simultaneous determination of chloramphenicol (CAP) and ractopamine (RAC) residues in 18 swine tissue samples, using anti-CAP and anti-RAC monoclonal antibodies labeled with europium (Eu3+) and samarium (Sm3+), respectively. The detection limits for CAP and RAC were 0.06 and 0.25 ng/g. The recovery from swine muscle samples was 102%–121% for CAP at spiking levels of 0.1–5 ng/g, and 69.8%–85.8% for RAC at spiking levels of 1–10 ng/g. The results obtained from the swine tissue samples using this method showed good agreement with those obtained using ELISA and GC-MS, with correlation coefficients (R) between 0.92–0.98.
Co-reporter:Rui Liu, Jing-fu Liu and Gui-bin Jiang
Chemical Communications 2010 vol. 46(Issue 37) pp:7010-7012
Publication Date(Web):23 Aug 2010
DOI:10.1039/C0CC02466J
By using Triton X-114 as structure-director and weak binding stabilizer, ultrathin Au, Pd and Pt nanowires are synthesized in seconds by reduction of inorganic metal precursors with KBH4 in aqueous phase. The nanowires show high catalytic activity and long-term stability toward electrooxidation of alcohols.
Co-reporter:Zhi-qiang Tan and Jing-fu Liu
Analytical Chemistry 2010 Volume 82(Issue 10) pp:4222
Publication Date(Web):April 20, 2010
DOI:10.1021/ac100541s
With the combination of the gold nanoparticle (AuNP)-based visual test with hollow fiber supported liquid membrane (HFSLM) extraction, a highly sensitive and selective method was developed for field detection of mercuric ion (Hg2+) in environmental waters. Hg2+ in water samples was extracted through HFSLM and trapped in the aqueous acceptor and then visually detected based on the red-to-blue color change of 3-mercaptopropionic acid-functionalized AuNP (MPA-AuNP) probe. The highest extraction efficiency of Hg2+ was obtained by using a 600 mL sample (pH 8.0, 2.0% (w/v) NaCl), ∼35 μL of acceptor (10 mM of 2,6-pyridinedicarboxylic acid, pH 4.0) filled in the lumen of a polypropylene hollow fiber tubing (55 cm in length, 50 μm wall thickness, 280 μm inner diameter), a liquid membrane of 2.0% (w/v) trioctycphosphine oxide in undecane, and a shaking rate of 250 rpm. The chromegenic reaction was conducted by incubating the mixture of MPA-AuNP stock solution (12 μL, 15 nM), Tris-borate buffer solution (18 μL, 0.2 M, pH 9.5), and acceptor (30 μL) at 30 °C for 1 h. The detection limit can be adjusted to 0.8 μg/L Hg2+ (corresponding to an enrichment factor of ∼1000 in the HFSLM) and 2.0 μg/L Hg2+ (the U.S. Environmental Protection Agency limit of [Hg2+] for drinkable water) by using extraction times of 3 and 1 h, respectively. The proposed method is extremely specific for Hg2+ with tolerance to at least 1000-fold of other environmentally relevant heavy and transition metal ions and was successfully applied to detect Hg2+ in a certified reference water sample, as well as real river, lake, and tap water samples.
Co-reporter:Zhen Zhang, Jing-fu Liu, Bing Shao and Gui-bin Jiang
Environmental Science & Technology 2010 Volume 44(Issue 3) pp:1030-1035
Publication Date(Web):December 29, 2009
DOI:10.1021/es903328b
Using monoclonal antibodies labeled with Eu3+ chelates, time-resolved fluoroimmunoassay (TRFIA) methods were developed for the determination of trace sulfamethazine (SMZ), sulfa-methoxazole (SMX), and sulfadiazine (SDZ) in environmental waters. Under the optimized conditions, the developed methods offered (i) low detection limits (9.8 ng/L SMZ, 6.1 ng/L SMX, and 5.4 ng/L SDZ, based on 90% inhibition) which were about 1 order of magnitude lower than that of the enzyme-linked immunosorbent assay (ELISA), (ii) high selectivity with no cross-reactivity (<0.05%) to similarly structured sulfonamides; (iii) high tolerance to variation of the sample pH (6.0−9.0) and salinity (0−100 mM), as well as the presence of humic acid (0−100 mg/L DOC) and heavy metals (0−1 mg/L concentration each of Cu2+, Cd2+, Hg2+, Pb2+, and As(V)) in the samples, and (iv) direct determination with low cost, high sample throughput, and low sample consumption (50−100 μL). The proposed TRFIA procedures were applied to determine sulfonamides in a variety of surface water and wastewater samples without sample pretreatment other than filtration. The satisfactory recoveries (64−127%) and reproducibilities (CV = 0.2−16%) achieved, as well as the good agreement with those given by liquid chromatography−tandem mass spectroscopy and ELISA methods, demonstrated the applicability of the proposed TRFIA methods for routine screening/quantification of sulfonamides in environmental waters.
Co-reporter:Yong-guang Yin, Ming Chen, Jin-feng Peng, Jing-fu Liu, Gui-bin Jiang
Talanta 2010 Volume 81(4–5) pp:1788-1792
Publication Date(Web):15 June 2010
DOI:10.1016/j.talanta.2010.03.039
A novel and simple solid phase extraction (SPE)-high performance liquid chromatography (HPLC)–inductively coupled plasma mass spectrometry (ICP-MS) method was developed for determination of inorganic mercury (IHg), methylmercury MeHg and ethylmercury (EtHg) in water samples in the present work. The procedure involves pre-functionalization of the commercially available C18 SPE column with dithizone, loading water sample, displacement elution of mercury species by Na2S2O3 solution, followed by HPLC–ICP-MS determination. Characterization and optimization of operation parameters of this new SPE procedure were discussed, including eluting reagent selection, concentration of eluting reagent, volume of eluting reagent, effect of NaCl and humic acid in sample matrix. At optimized conditions, the detection limits of mercury species for 100 mL water sample were about 3 ng L−1 and the average recoveries were 93.7, 83.4, and 71.7% for MeHg, IHg and EtHg, respectively, by spiking 0.2 μg L−1 mercury species into de-ion water. Stability experiment reveals that both the dithizone-functionalized SPE cartridge and the mercury species incorporated were stable in the storage procedure. These results obtained demonstrate that SPE-HPLC–ICP-MS is a simple and sensitive technique for the determination of mercury species at trace level in water samples with high reproducibility and accuracy.
Co-reporter:JingFu Liu;Jia Sun;GuiBin Jiang
Science Bulletin 2010 Volume 55( Issue 4-5) pp:346-349
Publication Date(Web):2010 February
DOI:10.1007/s11434-009-0695-0
Triton X-114 based cloud point extraction has been demonstrated to be an advantageous approach for the recovery of nanosized copper oxide (NCO) from water. The removal of NCO was influenced by the concentrations of TX-114 and salt, incubation temperature and time, as well as solution pH. With the addition of 0.3% (w/v) Triton X-114, over 88% of the spiked NCO was removed from wastewater after incubation at 35°C for 2 h and centrifugation, whereas over 85% of NCO was recovered after incubation at 28°C for 20 h by gravity phase separation, which is economical and energy-saving. This study suggests that the cloud point extraction technique has great potential in removal of nanomaterials from wastewater.
Co-reporter:Xia-lin Hu;Yuan-jian Huang;Yong Tao;Da-qiang Yin
Microchimica Acta 2010 Volume 168( Issue 1-2) pp:23-29
Publication Date(Web):2010 February
DOI:10.1007/s00604-009-0256-x
Traces of phenoxy acid herbicides and phenols were determined in environmental water samples by high performance liquid chromatography (HPLC) coupled to thin liquid film extraction (TLFE). A TLFE sampling device was prepared by dipping pieces of a polypropylene microporous hollow fiber membrane into dihexyl ether (containing 10% tri-n-octylphosphine oxide as carrier) for a few minutes to impregnate the pores of the hollow fiber wall. Extraction of analytes takes place from the outer aqueous phase into the immobilized solvent. After extraction the removal of the organic solvent was accomplished with a few µl of methanol which was used for HPLC analysis. Enrichment factors as high as 446 were obtained for the target compounds. The method provided detection limits as low as 0.4–1.2 µg L−1, good repeatability (the RSD ranging from 2.1 to 6.3%, n = 5) and a linear range from 2 to 200 µg L−1 for the target compounds. Real sample analysis showed recoveries between 84.6% and 112% for all compounds investigated.
Co-reporter:Zhi-qiang Tan, Jing-fu Liu, Rui Liu, Yong-guang Yin and Gui-bin Jiang
Chemical Communications 2009 (Issue 45) pp:7030-7032
Publication Date(Web):06 Oct 2009
DOI:10.1039/B915237G
Association with Hg2+ enhances the hydrophobicity and triggers the cloud point extraction of ∼4 nm-diameter gold nanoparticle probes functionalized with mercaptopropionic acid and homocystine, which results in the color change of the TX-114-rich phase from colorless to red, and therefore provides a novel approach for visual and colorimetric detection of Hg2+ with ultrahigh sensitivity and selectivity.
Co-reporter:Jing-fu Liu, Jing-bo Chao, Rui Liu, Zhi-qiang Tan, Yong-guang Yin, Yuan Wu and Gui-bin Jiang
Analytical Chemistry 2009 Volume 81(Issue 15) pp:6496
Publication Date(Web):July 6, 2009
DOI:10.1021/ac900918e
Silver nanoparticles (AgNPs) were selectively concentrated from environmental water samples without disturbing their sizes and shapes by cloud point extraction (CPE) with Triton X-114 (TX-114). The highest extraction efficiency for AgNPs was obtained at about their zero point charge pH (pHPZC), which was ∼3.0−3.5 for the studied AgNPs. Addition of salts such as 35 mM NaNO3 or 10 mM Na2S2O3 enhanced the phase separation and thus increased the extraction efficiency of AgNPs. Furthermore, Na2S2O3 efficiently eliminated the interference of Ag+ due to the formation of a complex between Ag+ and S2O32− that was not extracted into the TX-114-rich phase. The presence of humic acid at an environmentally relevant level (0−30 mg/L dissolved organic carbon) had no effect on the extraction of AgNPs. An enrichment factor of 100 was obtained with 0.2% (w/v) TX-114, and the recoveries of AgNPs from various environmental samples were in the range of 57−116% at 0.1−146 μg/L spiked levels. The AgNPs preconcentrated into the TX-114-rich phase were identified by transmission electron microscopy/scanning electron microscopy-energy dispersive spectrometer/UV−vis spectrum and quantified after microwave digestion by inductively coupled plasma mass spectrometry with a detection limit of 0.006 μg/L (34.3 fmol/L particles of AgNPs). As the proposed CPE procedure preserves the sizes and shapes of AgNPs, the original morphology of AgNPs in environmental waters can be obtained by characterizing the preconcentrated analytes in the TX-114-rich phase. This proposed method provides an efficient approach for the analysis and tracking of AgNPs in the environment.
Co-reporter:Jing-fu Liu, Xiao-qiang Cai, Zi-fu Li, Gui-bin Jiang
Journal of Chromatography A 2009 Volume 1216(Issue 12) pp:2583-2586
Publication Date(Web):20 March 2009
DOI:10.1016/j.chroma.2009.01.092
A new method based on negligible depletion hollow fiber-protected liquid-phase microextraction coupled with high-performance liquid chromatography (HPLC) was developed for the simultaneous determination of partitioning coefficients (KOW) and acid dissociation constants (pKa), by using phenol, 4-chlorophenol and 2,4-dichlorophenol as model compounds. A 37-mm length polypropylene hollow fiber membranes (600 μm inner diameter, 200 μm wall-thickness, 0.2 μm pore size, ∼70% porosity) with two-end sealed were filled with 1-octanol by ultrasonic agitation to prepare the extraction device. The extraction device was deployed in sample solutions, prepared by spiking target analytes in 1-octanol saturated aqueous solutions (500 mL), for negligible depletion extraction. After equilibrium was reached (∼5 h), the 1-octanol in the lumen of the hollow fiber membrane was collected for HPLC determination of the target analytes. As the depletion of the analytes in aqueous samples was negligible, the distribution coefficient (DOW) could be calculated based on the measured equilibrium concentration in 1-octanol (CO) and the initial concentration (CW) in the aqueous sample of the target analyte (DOW = CO/CW). The DOW values measured at various pH values were nonlinearly regressed with pH to obtain the KOW and pKa values of a compound. Results showed that the measured values of the KOW and pKa of these model compounds agreed well with literature data.
Co-reporter:Yong-guang Yin, Zhen-hua Wang, Jin-feng Peng, Jing-fu Liu, Bin He and Gui-bin Jiang
Journal of Analytical Atomic Spectrometry 2009 vol. 24(Issue 11) pp:1575-1578
Publication Date(Web):08 Sep 2009
DOI:10.1039/B907169E
A high performance liquid chromatography-direct chemical vapour generation-flame atomization-atomic fluorescence spectrometry (HPLC-CVG-FA-AFS) system for speciation of methylmercury (MeHg+), inorganic mercury (Hg2+) and ethylmercury (EtHg+) without using post-column digestion is developed and characterized. In this novel system, organomercurial species separated by chromatography were transformed to their hydrides by KBH4, further atomized in the flame atomizer and detected by AFS. The conventionally used on-line UV or microwave digestion system was omitted, and no oxidation reagent was needed, which significantly simplified the instrumentation. Under the optimized conditions, the detection limits were 0.2, 0.4 and 0.4 µg L−1 (as Hg) for MeHg+, Hg2+, and EtHg+ (100 µL injection), which corresponds to absolute detection limits of 0.02, 0.04 and 0.04 ng (as Hg) for MeHg+, Hg2+, and EtHg+, respectively. The sensitivity of the developed method was comparable with the conventional high performance liquid chromatography-UV digestion-cold vapour generation-atomic fluorescence spectrometry (HPLC-UV-CVG-AFS) system. Validation with biological certified reference materials showed that the proposed method is simple and accurate for mercury speciation.
Co-reporter:Xialin Hu;Jinfeng Peng;Yuanjian Huang;Daqiang Yin;Jingfu Liu
Journal of Separation Science 2009 Volume 32( Issue 23-24) pp:4126-4132
Publication Date(Web):
DOI:10.1002/jssc.200900538
Abstract
In this present study, 1-butyl-3-methylimidazolium chloride ([C4MIM]Cl), 1-octyl-3-methylimidazolium chloride ([C8MIM]Cl), and 1-decyl-3-methylimidazolium chloride ([C10MIM]Cl) were adopted as mobile phase additives in the high performance liquid chromatography (HPLC) to simultaneously separate phenoxy acid herbicides and phenols at neutral pH. It was found that by using 20 mM of [C4MIM]Cl, baseline separation and good chromatograms for all the acid compounds were obtained on a normal reversed-phase C18 column. The retention time of the target acid compounds shortened with the increase of the alkyl chain length and the concentrations of ionic liquids, probably due to the delocalization of the positive charge on the imidazolium cation, the repulsion between chlorine ions of ionic liquids and the acid compounds, as well as the stereo-hindrance effect. The mechanism with ionic liquids as mobile additives for the separation of acid compounds was discussed.
Co-reporter:Yongguang Yin;Jingfu Liu;Bin He;Jianbo Shi;Guibin Jiang
Microchimica Acta 2009 Volume 167( Issue 3-4) pp:
Publication Date(Web):2009 December
DOI:10.1007/s00604-009-0250-3
Speciation of mercury was accomplished by using a simple interface with photo-induced chemical vapour generation in a high performance liquid chromatography—atomic fluorescence spectrometry (HPLC-AFS) hyphenated system. Acetic acid and 2-mercaptoethanol in the mobile phase were used as photochemical reagent. The operating parameters were optimized to give limits of detection of 0.53 µg L−1, 0.22 µg L−1, 0.18 µg L−1 and 0.25 µg L−1 for inorganic mercury, methylmercury, ethylmercury and phenylmercury, respectively. The method was validated with the certified reference material DORM-2 and applied to the analysis of seafood samples. The HPLC-AFS hyphenated system is simple, environmentally friendly, and represents an attractive alternative to the conventional peroxothiosulfate-borohydride method.
Co-reporter:Rui Liu;Yong-guang Yin;Xia-lin Hu
Analytical and Bioanalytical Chemistry 2009 Volume 393( Issue 3) pp:871-883
Publication Date(Web):2009 February
DOI:10.1007/s00216-008-2445-6
Due to their unique properties, their good extractabilities for various target analytes, and the fact that many compounds are highly soluble in them, room-temperature ionic liquids (ILs) are used as promising alternatives to the traditional organic solvents employed in sample preparation. ILs have been used as extraction solvents for a wide range of analytes, from environmental contaminates to biomacromolecules and nanomaterials, and as dissolution solvents for various detection techniques. In this paper, the main applications of ILs in sample preparation are reviewed, and the problems and challenges in this area are described.
Co-reporter:Dan-dan Cao, Jian-xia Lü, Jing-fu Liu, Gui-bin Jiang
Analytica Chimica Acta 2008 Volume 611(Issue 1) pp:56-61
Publication Date(Web):17 March 2008
DOI:10.1016/j.aca.2008.01.067
Nanostructured titania-based solid-phase microextraction (SPME) fibers were fabricated through the in situ oxidation of titanium wires with H2O2 (30%, w/w) at 80 °C for 24 h. The obtained SPME fibers possess a ∼1.2 μm thick nanostructured coating consisting of ∼100 nm titania walls and 100–200 nm pores. The use of these fibers for headspace SPME coupled with gas chromatography with electron capture detection (GC–ECD) resulted in improved analysis of dichlorodiphenyltrichloroethane (DDT) and its degradation products. The presented method to detect DDT and its degradation products has high sensitivity (0.20–0.98 ng L−1), high precision (relative standard deviation R.S.D. = 9.4–16%, n = 5), a wide linear range (5–5000 ng L−1), and good linearity (coefficient of estimation R2 = 0.991–0.998). As the nanostructured titania was in situ formed on the surface of a titanium wire, the coating was uniformly and strongly adhered on the titanium wire. Because of the inherent chemical stability of the titania coating and the mechanical durability of the titanium wire substrate, this new SPME fiber exhibited long life span (over 150 times).
Co-reporter:Jin-feng Peng, Ke-teng Fang, Dong-hua Xie, Bin Ding, Ju-Yi Yin, Xiao-mei Cui, Ying Zhang, Jing-fu Liu
Journal of Chromatography A 2008 Volume 1209(1–2) pp:70-75
Publication Date(Web):31 October 2008
DOI:10.1016/j.chroma.2008.09.028
An improved sensitive method was developed and validated for the determination of histamine in food samples by using automated on-line pre-column derivatization coupled with high performance liquid chromatography and fluorescence detection (HPLC–FLD). o-Phthaldialdehyde (OPA) was adopted as derivatization reagent, and a “sandwich” (OPA + histamine + OPA) aspiration mode for the automated on-line pre-column derivatization was found to efficiently enhance the method sensitivity and precision. Histamine in food samples was efficiently extracted with a methanol–phosphate buffer solution (50:50, v/v) at 60 °C for 30 min, and purified with Waters Oasis MCX solid-phase extraction (SPE) cartridge. The limit of quantification for this method is 0.2 mg/kg, which is very sensitive for histamine determination. With the “sandwich” injection program, 3.7% of relative standard deviation (RSD) was achieved by five replicative determinations of a sample blank spiked with 0.25 mg/kg histamine standard. Histamine in food samples such as fumitory skipjack and mackerel was analyzed with relative recoveries over 95% at spiking level of 150 mg/kg, as well as canned tuna fish and cheese with relative recoveries up to 98% at spiking levels of 0.50 and 5.0 mg/kg, respectively. The proposed method was validated with a sample from the Food Analysis Performance Assessment Scheme (FAPAS) as a standard certified material; and the results (140 ± 6 mg/kg) agreed well with the assigned value (139 mg/kg).
Co-reporter:Jinfeng Peng;Jianxia Lü;Xialin Hu;Jingfu Liu;Guibin Jiang
Microchimica Acta 2007 Volume 158( Issue 1-2) pp:181-186
Publication Date(Web):2007 April
DOI:10.1007/s00604-006-0692-9
A new method based on hollow fiber-protected liquid-phase microextraction (LPME) was developed for the simultaneous determination of atrazine, desethyl atrazine and desisopropyl atrazine in environmental water samples. In LPME, analytes were extracted into 1-octanol immobilized in the micropores of a poly(vinylidene fluoride) porous hollow fiber membrane, and back extracted into the acceptor (4 M HCl) filled in the lumen of the hollow fiber. After LPME, the analytes trapped in the acceptor were analyzed with high-performance liquid chromatography after neutralization. The effect of extraction factors such as sample pH, acceptor pH, salinity, extraction time, stirring rate, and humic acid were studied. Under the optimized conditions, the limits of detection and relative standard deviations were respectively in the range of 0.5–1.0 µg L−1 and 3.9–4.7% (n = 5). The proposed method was applied to determine atrazine, desethyl atrazine and desisopropyl atrazine in wastewater and groundwater samples. The three analytes were below the limits of detection, but good relative spiked recoveries over 90.1 ± 5.9% at 5 µg L−1 spiked level were obtained.
Co-reporter:Yongguang Yin, Dan Han, Chao Tai, Zhiqiang Tan, Xiaoxia Zhou, Sujuan Yu, Jingfu Liu, Guibin Jiang
Environmental Pollution (June 2017) Volume 225() pp:66-73
Publication Date(Web):1 June 2017
DOI:10.1016/j.envpol.2017.03.048
•AgNP was characterized and quantified in photo-irradiated Ag+-DOM-Fe2+/3+ systems.•Iron enhanced the formation of AgNP in photo-irradiated Ag+-DOM solution.•AgNP formation was enhanced with the increase of DOM concentration.•The enhancement effect of iron was more significant at lower pH.•Other electron shuttles could also possibly enhance the formation of AgNPs.Photo-reduction of Ag+ to silver nanoparticle (AgNPs) by dissolved organic matter (DOM) is a possible source of naturally occurring AgNPs. However, how this photo-reduction process is influenced by ubiquitous metal ions is still not well understood. In addition, in previous studies, the formation of AgNPs in DOM solution was usually monitored by UV-Vis spectroscopy, and there is still lack of quantitative analysis for the formed AgNPs. In the present study, the role of Fe2+/Fe3+ at environmental concentration level on this photochemical process was investigated, and the enhanced formation of AgNPs by Fe2+/Fe3+ was probed and quantified by using UV-Vis spectroscopy, transmission electron microscopy, and liquid chromatography-inductively coupled plasma mass spectrometry. It was demonstrated that while Fe3+ can oxidize AgNPs to release Ag+, Fe2+ can reduce Ag+ into AgNPs. However, the DOM-induced reduction of Fe3+ makes iron an effective electron shuttle between DOM and Ag+, and both Fe2+ and Fe3+ enhanced AgNP formation. The impacts of environmentally relevant factors, including DOM concentration and solution pH, on this process were studied comprehensively, which showed that the catalytic role of iron was more significant at higher DOM concentration and lower pH. This iron-enhanced formation of AgNPs in photo-irradiated Ag+-DOM solution have great environmental implications on the formation of natural AgNPs and the transformation of engineered AgNPs in acidic surface water with high iron content.Download high-res image (323KB)Download full-size image
Co-reporter:Xiao-Xia Zhou, Jing-Fu Liu, Fang-Lan Geng
NanoImpact (January 2016) Volume 1() pp:13-20
Publication Date(Web):1 January 2016
DOI:10.1016/j.impact.2016.02.002
•SEC-ICP-MS was applied to speciation analysis of metal ions and metal oxide nanoparticles.•Baseline separation of metal ions and metal oxide nanoparticles in 10 min•Detection limits at ng/L levels for both metal ions and metal oxide nanoparticles•Applicable for various environmental watersAnalysis of metal oxide nanoparticles (MO NPs) and their released metal ions (Mn+) is essential for understanding their environmental effects and biological toxicity. For the first time, size exclusion chromatography (SEC) was coupled with inductively coupled plasma mass spectrometry (ICP-MS) for speciation analysis of MO NPs and their corresponding Mn+. By using a 1000 Å poresize silica column, and an acetate buffer (pH 7.0, 10 mM) containing 10 mM sodium dodecyl sulfate (SDS) as a mobile phase at a flow rate of 0.5 mL/min, Mn+ and MO NPs with sizes smaller than the column poresize were baseline separated within 10 min, whereas MO NPs with sizes larger than the exclusion limit were filtered off by the column. More importantly, this mobile phase is able to avoid the dissolution of MO NPs during the SEC separation. The high recoveries (> 97%) of Mn+ from the SEC column ensured their accurate quantification directly with the online coupled SEC-ICP-MS, while the quantification of MO NPs by subtracting the Mn+ content from the total metal content, which was determined with ICP-MS after digestion without SEC separation, efficiently eliminating the influence of retention of large MO NPs in the column. MO NPs with different sizes and compositions including NiO, CoO, ZnO, CuO and CeO2 NPs were analyzed with this proposed method, with low detection limits (0.016–0.390 μg/L for both Mn+ and MO NPs) and relative standard deviations (< 0.4% for retention time and < 2.2% for peak area at 50 μg/L Mn+). The proposed method was verified by analyzing Ni2+, Ce4+, NiO and CeO2 NPs in various environmental waters, with spiked recoveries in the range of 80.8–105.1%. Our method has great potential for speciation analysis of MO NPs and their corresponding Mn+ in the environmental waters.Download high-res image (123KB)Download full-size image
Co-reporter:Xialin Hu, Jingfu Liu, Qunfang Zhou, Shiyan Lu, Rui Liu, Lin Cui, Daqiang Yin, Philipp Mayer, Guibin Jiang
Chemosphere (August 2010) Volume 80(Issue 7) pp:693-700
Publication Date(Web):1 August 2010
DOI:10.1016/j.chemosphere.2010.05.042
The wide application of engineered nanomaterials, such as fullerene (C60), will inevitably lead to their release into the aqueous environment, which may alter the bioavailability of organic compounds to aquatic organisms. Negligible depletion solid-phase microextraction (nd-SPME) together with medaka (Oryzias latipes) bioaccumulation were used to study the effects of aqueous suspensions of fullerene (nC60) on the bioavailability of eight organochlorine compounds (OCCs) (log KOW 3.76–6.96). Freely dissolved concentrations of OCCs decreased by 11.5–88.4% at addition of 5 mg L−1 nC60 as indicated by reduced equilibrium concentrations in the SPME fiber coating, the highest reduction being observed for the most hydrophobic OCCs. Medaka bioaccumulation study demonstrated that at the kinetic uptake regime, nC60 significantly decreased the bioaccumulation of the high hydrophobic OCCs (log KOW > 6), but slightly enhanced the bioaccumulation of the less hydrophobic OCCs (log KOW < 6). The OCC concentrations in medaka (Cfish) at the kinetic uptake regime linearly correlated with that in nd-SPME fiber (Cfiber) without nC60 (p = 0.007–0.013, R2 = 0.666–0.723), but this correlation deteriorated with the presence of nC60 (p = 0.073–0.081, R2 = 0.423–0.440). These results suggest that in nC60 the uptake mechanism of OCCs to medaka is different from that to nd-SPME fiber. While only the freely dissolved OCCs are available to nd-SPME fiber, both the freely dissolved and the nC60 associated OCCs contributed to the accumulation of OCCs to medaka.
Co-reporter:Kang Liang, Yumin Niu, Yongguang Yin, Jingfu Liu
Journal of Environmental Sciences (1 August 2015) Volume 34() pp:57-62
Publication Date(Web):1 August 2015
DOI:10.1016/j.jes.2015.01.022
Organophosphate esters (OPEs), used as flame retardants and plasticizers, are widely present in environmental waters. Development of accurate determination methods for trace OPEs in water is urgent for understanding the fate and risk of this class of emerging pollutants. However, the wide use of OPEs in experimental materials results in blank interference, which influences the accuracy of analytical results. In the present work, blank contamination and recovery of pretreatment procedures for analysis of OPEs in water samples were systematically examined for the first time. Blank contaminations were observed in filtration membranes, glass bottles, solid phase extraction cartridges, and nitrogen blowing instruments. These contaminations could be as high as 6.4–64 ng/L per treatment. Different kinds of membranes were compared in terms of contamination levels left after common glassware cleaning, and a special wash procedure was proposed to eliminate the contamination from membranes. Meanwhile, adsorption of highly hydrophobic OPEs on the inside wall of glass bottles was found to be 42.4%–86.1%, which was the primary cause of low recoveries and was significantly reduced by an additional washing step with acetonitrile. This work is expected to provide guidelines for the establishment of analysis methods for OPEs in aqueous samples.Download full-size image
Co-reporter:Yongguang Yin, Xiaoya Yang, Xiaoxia Zhou, Weidong Wang, ... Guibin Jiang
Journal of Environmental Sciences (1 August 2015) Volume 34() pp:116-125
Publication Date(Web):1 August 2015
DOI:10.1016/j.jes.2015.04.005
The inevitable release of engineered silver nanoparticles (AgNPs) into aquatic environments has drawn great concerns about its environmental toxicity and safety. Although aggregation and transformation play crucial roles in the transport and toxicity of AgNPs, how the water chemistry of environmental waters influences the aggregation and transformation of engineered AgNPs is still not well understood. In this study, the aggregation of polyvinylpyrrolidone (PVP) coated AgNPs was investigated in eight typical environmental water samples (with different ionic strengths, hardness, and dissolved organic matter (DOM) concentrations) by using UV–visible spectroscopy and dynamic light scattering. Raman spectroscopy was applied to probe the interaction of DOM with the surface of AgNPs. Further, the photo-transformation and morphology changes of AgNPs in environmental waters were studied by UV–visible spectroscopy, inductively coupled plasma mass spectrometry, and transmission electron microscopy. The results suggested that both electrolytes (especially Ca2 + and Mg2 +) and DOM in the surface waters are key parameters for AgNP aggregation, and sunlight could accelerate the morphology change, aggregation, and further sedimentation of AgNPs. This water chemistry controlled aggregation and photo-transformation should have significant environmental impacts on the transport and toxicity of AgNPs in the aquatic environments.Download full-size image
Co-reporter:Su-juan Yu, Yong-guang Yin and Jing-fu Liu
Environmental Science: Nano 2013 - vol. 15(Issue 1) pp:NaN92-92
Publication Date(Web):2012/12/06
DOI:10.1039/C2EM30595J
Silver nanoparticles (AgNPs) are well known for their excellent antibacterial ability and superior physical properties, and are widely used in a growing number of applications ranging from home disinfectants and medical devices to water purificants. However, with the accelerating production and introduction of AgNPs into commercial products, there is likelihood of release into the environment, which raises health and environmental concerns. This article provides a critical review of the state-of-knowledge about AgNPs, involving the history, analysis, source, fate and transport, and potential risks of AgNPs. Although great efforts have been made in each of these aspects, there are still many questions to be answered to reach a comprehensive understanding of the positive and negative effects of AgNPs. In order to fully investigate the fate and transport of AgNPs in the environment, appropriate methods for the preconcentration, separation and speciation of AgNPs should be developed, and analytical tools for the characterization and detection of AgNPs in complicated environmental samples are also urgently needed. To elucidate the environmental transformation of AgNPs, the behavior of AgNPs should be thoroughly monitored in complex environmental relevant conditions. Furthermore, additional in vivo toxicity studies should be carried out to understand the exact toxicity mechanism of AgNPs, and to predict the health effects to humans.
Co-reporter:
Analytical Methods (2009-Present) 2014 - vol. 6(Issue 1) pp:NaN169-169
Publication Date(Web):2013/10/29
DOI:10.1039/C3AY41625A
Species-specific isotope dilution (SSID) in combination with gas chromatography-inductively coupled plasma-mass spectrometry (GC-ICP-MS) has been developed for the separation and determination of methylmercury (MeHg) in water, sediments and biological tissues. Optimum conditions for the measurement of isotope ratios on the transient chromatographic peaks have been established. SSID analysis was performed using a laboratory synthesized enriched spike of Me198Hg. Isotope ratio precision based on the peak area measurements was 1.4% RSD for 50 pg (as Hg). The absolute detection limits obtained with GC-ICP-MS were 4.3 pg for 198Hg and 8.1 pg for 202Hg, respectively. Analytical precision was typically less than 3.6% RSD over eight repeated measurements. The accuracy of the method has been compared with the method with Tl as internal standard and further validated with certified reference materials (ERM-cc580 for sediments and Tort-2 for the biological tissues). The results obtained by SSID-GC-ICP-MS were in good agreement with the certified reference values.
Co-reporter:Xiaoxia Zhou, Jingfu Liu, Chungang Yuan and Yongsheng Chen
Journal of Analytical Atomic Spectrometry 2016 - vol. 31(Issue 11) pp:NaN2292-2292
Publication Date(Web):2016/09/20
DOI:10.1039/C6JA00243A
The growing production and widespread application of silver nanoparticles (AgNPs) have led to their release into the environment, where they are mostly transformed to silver sulfide nanoparticles (Ag2S NPs). Thus, speciation analysis of Ag2S NPs in environmental matrices is essential for understanding the environmental process and toxic effects of AgNPs. Herein, we report the use of aged iron oxide magnetic particles (IOMPs) as magnetic solid-phase extraction adsorbents for speciation analysis of Ag2S NPs. It was found that IOMPs are excellent adsorbents for the selective extraction of silver-containing nanoparticles (AgCNPs) including Ag2S NPs, AgNPs and AgCl NPs in the presence of Ag+. More importantly, Ag2S NPs can be distinguished from the other AgCNPs by sequential elution. After pre-eluting AgNPs and AgCl NPs as Ag+ with 2% (v/v) acetic acid and IOMPs as the sacrificial oxidants, Ag2S NPs were completely eluted as a Ag(I) complex by 10 mM thiourea in 2% (v/v) acetic acid and quantified directly by inductively coupled plasma mass spectrometry (ICP-MS). While the extraction of Ag+ was negligible, the maximum extraction of AgCNPs by IOMPs was attained at pH 4.9–6.2, and the interference of humic acid in the AgCNP extraction can be efficiently eliminated by adding Ca2+. Under optimized conditions, the method provides low detection limit (0.068 μg L−1) and high reproducibility (relative standard deviations < 5.1%) for Ag2S NPs. By simultaneously spiking 0.16–10.3 μg L−1 AgNPs and 0.53–14.8 μg L−1 Ag2S NPs, the Ag2S NP recoveries were in the range of 69.6–100.2% for the tap, river and lake waters; and in the range of 106.2–149.9% for the WWTP effluent due to the part sulfidation of AgNPs to Ag2S NPs. Our method is valid for the speciation analysis of Ag2S NPs in water samples, which provides an efficient approach for studying the sulfidation of AgNPs and Ag+.
Co-reporter:
Analytical Methods (2009-Present) 2014 - vol. 6(Issue 9) pp:NaN3033-3033
Publication Date(Web):2014/02/03
DOI:10.1039/C4AY00022F
A one-step microwave-assisted extraction (MAE) procedure for highly efficient multiresidue extraction of seven fungicides (cymoxanil, metalaxyl, mandipropamid, folpet, chlorothalonil, kresoxim-methyl and famoxadone) in soil was developed. The trace residue levels in the soil were determined by high performance liquid chromatography (HPLC) with variable wavelength detection (VWD). Parameters affecting the MAE process such as the type and volume of the extraction solvent, irradiation power, temperature, irradiation time, moisture and salt addition were optimized. Under the optimal conditions, extraction efficiencies in the range of 72.4–99.4% were obtained for all the fungicides studied. The method was linear over the range of 0.01–10 μg g−1 with correlation coefficients (r2) between 0.9989 and 0.9999. LODs (S/N = 3) and LOQs (S/N = 10) obtained varied from 0.0006 to 0.0015 μg g−1 and from 0.002 to 0.005 μg g−1, respectively. The proposed method has been successfully applied to the analysis of real soil samples and acceptable recoveries from 57.5 to 122% with RSDs ≤14% were obtained. The overall results have been compared with Soxhlet, shake-flask and ultrasonic solvent extraction techniques. Thus, the developed method could be efficiently used for selective extraction and determination of the target analytes from complex soil matrices.
Co-reporter:Rui Liu, Jing-fu Liu, Su-juan Yu, Qian Liu and Gui-bin Jiang
Chemical Communications 2011 - vol. 47(Issue 5) pp:NaN1615-1615
Publication Date(Web):2010/11/26
DOI:10.1039/C0CC04490C
Ultrafine ligament noble metal nanoporous films are successfully fabricated by self-organization of ultrathin nanowires. The replacement of weak binding capping agent Triton X-114, used for stabilizing nanowires, by Cl− is claimed for this self-organization. Our method is also applicable for synthesizing other hierarchical nanostructure-like hybrid nanoporous films.
Co-reporter:Rui Liu, Jing-Fu Liu, Li-Qiang Zhang, Jie-Fang Sun and Gui-Bin Jiang
Journal of Materials Chemistry A 2016 - vol. 4(Issue 20) pp:NaN7614-7614
Publication Date(Web):2016/03/10
DOI:10.1039/C6TA01217E
Here, we report a versatile and simple route for the preparation of graphene-like, single-crystalline superparamagnetic γ-Fe2O3 nanosheets (NSs) as superior inorganic arsenic sorbents. Benefiting from their large surface area and abundant hydroxyl groups, γ-Fe2O3 NSs can sequestrate up to 109.5 and 39.1 mg g−1 of As(III) and As(V) ions within 15 min. Moreover, after screening the electrostatic repulsion, ca., through the introduction of a salt or changing solution pH, the removal efficiency of As(V) was enhanced to that of As(III). Besides showing similar adsorption capacity, O1s XPS and As K-edge EXAFS revealed that As(III) and As(V) are captured on the γ-Fe2O3 NSs via the formation of an identical but uncommon monodentate mononuclear (1V) complex. Such a configuration is favorable for the accommodation of more arsenic ions, and therefore reduces the surface energy of the ultrathin NSs more effectively than other complexion modes. Our study demonstrates the feasibility of solving an environmental problem through material innovation, and the foreground of application of 2D materials for environmental improvement.
Co-reporter:Sujuan Yu, Yongguang Yin, Xiaoxia Zhou, Lijie Dong and Jingfu Liu
Environmental Science: Nano 2016 - vol. 3(Issue 4) pp:NaN893-893
Publication Date(Web):2016/06/24
DOI:10.1039/C6EN00104A
Silver nanoparticles (AgNPs) are rather mutable in water columns, and the oxidation of AgNPs to release Ag+ and reduction of Ag+ to regenerate AgNPs exist simultaneously in certain environments, making it rather difficult to monitor the reaction kinetics. In this study, we synthesized isotopically labeled AgNPs (99.5% 107Ag, 107AgNPs) and AgNO3 (99.81% 109Ag, 109AgNO3). For the first time, two stable Ag isotopes were used in the same experiment to track the transformation kinetics of AgNPs and Ag+ independently in aquatic environments. It was found that the oxidation of AgNPs dominated the reaction in simple water solutions containing both 107AgNPs and 109Ag+. Sunlight significantly accelerated the dissolution of the 107AgNPs, but longer solar irradiation (8 h) triggered aggregation of the 107AgNPs and therefore reduced the reaction rate. With the addition of 5 mg C L−1 dissolved organic matter, the reduction of 109Ag+ played the leading role. The corrected concentration of dissolved 107Ag+ began to decrease after some time, indicating other reduction mechanisms were happening. An elevated pH (pH 8.5) could even completely inhibit the oxidation of 107AgNPs. All the reactions seemed stalled at low temperature (6 °C) except the dissolution of 107AgNPs under solar irradiation, suggesting a non-negligible effect of sunlight. The presence of divalent cations induced agglomeration of 107AgNPs, but the reduction of 109Ag+ was not significantly affected. These findings implied that the transformation between AgNPs and Ag+ was rather complex and greatly depended on the external conditions. Given the fact that Ag+ has been shown to be much more toxic than AgNPs, the speciation change may dramatically impact the final toxicity and bioavailability of AgNPs, so there is a high demand for assessing the environmental risks of AgNPs under more realistic conditions.
Co-reporter:Rui Liu, Jie-fang Sun, Dong Cao, Li-qiang Zhang, Jing-fu Liu and Gui-bin Jiang
Chemical Communications 2015 - vol. 51(Issue 7) pp:NaN1312-1312
Publication Date(Web):2014/11/18
DOI:10.1039/C4CC08016E
In this report, we propose and demonstrate the fabrication of a highly-specific SERS substrate, which was achieved by the co-precipitation of functional materials, such as nanosorbents and nanocatalysts, into Ag nanoporous films. Based on the nanostructures developed, we performed the ultrasensitive detection of arsenic ions by SERS and monitored the catalyzed reactions using real-time SERS.
Co-reporter:Yong-guang Yin, Zhen-hua Wang, Jin-feng Peng, Jing-fu Liu, Bin He and Gui-bin Jiang
Journal of Analytical Atomic Spectrometry 2009 - vol. 24(Issue 11) pp:NaN1578-1578
Publication Date(Web):2009/09/08
DOI:10.1039/B907169E
A high performance liquid chromatography-direct chemical vapour generation-flame atomization-atomic fluorescence spectrometry (HPLC-CVG-FA-AFS) system for speciation of methylmercury (MeHg+), inorganic mercury (Hg2+) and ethylmercury (EtHg+) without using post-column digestion is developed and characterized. In this novel system, organomercurial species separated by chromatography were transformed to their hydrides by KBH4, further atomized in the flame atomizer and detected by AFS. The conventionally used on-line UV or microwave digestion system was omitted, and no oxidation reagent was needed, which significantly simplified the instrumentation. Under the optimized conditions, the detection limits were 0.2, 0.4 and 0.4 µg L−1 (as Hg) for MeHg+, Hg2+, and EtHg+ (100 µL injection), which corresponds to absolute detection limits of 0.02, 0.04 and 0.04 ng (as Hg) for MeHg+, Hg2+, and EtHg+, respectively. The sensitivity of the developed method was comparable with the conventional high performance liquid chromatography-UV digestion-cold vapour generation-atomic fluorescence spectrometry (HPLC-UV-CVG-AFS) system. Validation with biological certified reference materials showed that the proposed method is simple and accurate for mercury speciation.
Co-reporter:Zhi-qiang Tan, Jing-fu Liu, Rui Liu, Yong-guang Yin and Gui-bin Jiang
Chemical Communications 2009(Issue 45) pp:NaN7032-7032
Publication Date(Web):2009/10/06
DOI:10.1039/B915237G
Association with Hg2+ enhances the hydrophobicity and triggers the cloud point extraction of ∼4 nm-diameter gold nanoparticle probes functionalized with mercaptopropionic acid and homocystine, which results in the color change of the TX-114-rich phase from colorless to red, and therefore provides a novel approach for visual and colorimetric detection of Hg2+ with ultrahigh sensitivity and selectivity.
Co-reporter:
Analytical Methods (2009-Present) 2013 - vol. 5(Issue 4) pp:
Publication Date(Web):
DOI:10.1039/C2AY26216A
Hollow fiber supported liquid membrane (HFSLM) extraction often suffers from matrix effects in extracting weak organic acids in environmental waters, but the reasons for which are unclear. This work systematically studied the influence of dissolved carbon dioxide and carbonate on the HFSLM extraction of analytes in environmental waters, by using triclosan and its two typical degradation products, 2,4-dichlorophenol and 2,4,6-trichlorophenol, as model compounds. HFSLM was conducted by immersing a HFSLM extraction device into a 200 mL water sample modified with 0.01 M HCl and 10% (m/v) NaCl, and shaking at 250 rpm for 90 min. The extraction device was prepared by immobilizing dihexyl ether on the polypropylene hollow fiber membrane wall (60 cm length, 50 μm wall thickness, 280 μm inner diameter), filling the fiber lumen with 0.4 M NaOH as acceptor, and closing the two ends of the fiber with aluminum foil. It was demonstrated that the dissolved carbon dioxide and carbonate present in environmental samples reduces the acceptor pH and thus the recovery of target analytes, and purging the acidified sample with ∼50 mL min−1 N2 for 15 min is a very efficient approach to eliminate this matrix effect. With this purging pretreatment, the recoveries of the analytes in environmental samples increased substantially from below 40% to between 63% and 121%. For the three analytes, the proposed HFSLM method provided enrichment factors in the range of 1090–1322, and detection limits in the range of 0.1–0.2 μg L−1 by coupling with an ultra-performance liquid chromatography-mass spectrometry system.
Co-reporter:Jing-Fu Liu, Yong Tao, Jia Sun and Gui-Bin Jiang
Analytical Methods (2009-Present) 2011 - vol. 3(Issue 3) pp:NaN702-702
Publication Date(Web):2011/02/15
DOI:10.1039/C0AY00670J
A new passive sampling device was developed for field equilibrium sampling of geosmin (GSM) and 2-methylisoborneol (MIB) in surface water. The sampling device was prepared by coating a 50 cm length polypropylene hollow fiber tubing (50 μm wall thickness, 280 μm inner diameter) with polypropylene glycol 4000. The sampler was brought into equilibrium with the sample in the field, and then transferred and immersed into 100 μL of methanol held in a little desorption device for room temperature desorption and preservation of the sampled analytes. After being transported to the laboratory, the analytes were determined by headspace solid-phase microextraction-GC-MS. The large surface area-to-volume ratio of the developed sampler facilitated the reaching of sampling equilibrium in 1 h, while the equilibrium sampling minimized the effects of environmentally relevant sampling conditions. Variation of sample pH (4.0–9.0) and salinity (0–100 mM NaCl) had no significant effects on the distribution coefficients of analytes to the sampler. The desorption device, constructed with a 200 μL glass insert, and a 2 mL brown glass vial with PTFE sealed screw cap, has no loss of analytes during the storage of the sampler. The proposed procedure had detection limits of 4 and 9 ng L−1 for GSM and MIB, respectively. This developed sampler was successfully applied to field sampling in Taihu Lake (China), with MIB and GSM detected in the range of 0.11–0.61 μg L−1 during a medium out-break of blue–green algae bloom.
Co-reporter:Rui Liu, Jing-fu Liu and Gui-bin Jiang
Chemical Communications 2010 - vol. 46(Issue 37) pp:NaN7012-7012
Publication Date(Web):2010/08/23
DOI:10.1039/C0CC02466J
By using Triton X-114 as structure-director and weak binding stabilizer, ultrathin Au, Pd and Pt nanowires are synthesized in seconds by reduction of inorganic metal precursors with KBH4 in aqueous phase. The nanowires show high catalytic activity and long-term stability toward electrooxidation of alcohols.
Co-reporter:
Analytical Methods (2009-Present) 2012 - vol. 4(Issue 4) pp:
Publication Date(Web):
DOI:10.1039/C2AY05886C
Volatile species generation-flameless/flame atomization-atomic fluorescence spectrometry (VSG-FL/FA-AFS) without chromatographic separation was developed for quantitative determination of inorganic mercury (IHg) and methylmercury (MeHg) in water and biological samples by using a commercially available atomic fluorescence spectrometer. In the proposed method, inorganic mercury was measured by using the flameless mode. However, by using the flame atomization mode, the volatile hydride of MeHg generated by KBH4 can be transformed to elemental mercury vapour in the reductive argon–hydrogen flame, and both MeHg and IHg give a fluorescence signal in this flame atomization mode. Then, the concentration of MeHg can be calculated by subtracting IHg concentration from the total mercury concentration. The limits of detection for IHg and MeHg were 0.03 μg L−1 and 0.05 μg L−1, respectively. Spiked environmental water samples including seawater, tap water and river water were determined and satisfactory recoveries were obtained for MeHg and IHg. Furthermore, the proposed method was successfully applied to analyze biological certified reference material, TORT-2 (lobster hepatopancreas).
