Co-reporter:Chen Xu;Li Ling;Jiajun Zhu;Jiakun Long;Yingjia Yu
Chromatographia 2017 Volume 80( Issue 2) pp:335-340
Publication Date(Web):2017 February
DOI:10.1007/s10337-016-3230-x
Infrared radiation, one form of electromagnetic wave, has potential value due to its heating effect, but has become a matter of grave concern in recent years. We describe herein ionic-liquid-based infrared-assisted extraction (IL-IRAE) coupled with high-performance liquid chromatography (HPLC)–mass spectrometry (MS) as a green and convenient method for simultaneous determination of three alkaloids in Lycoris radiata, a traditional Chinese medicine (TCM). Extraction parameters including the type and concentration of IL, extraction solvent, liquid/solid ratio, extraction time, and irradiation power were optimized via orthogonal design and analysis of variance (ANOVA). Chromatography–mass spectrometry was performed in positive ion mode on a TSK gel C18 column (150 mm × 4.6 mm id, 5-µm particle size) with less than 5-min separation. Evaluation of the method showed good results with analytical recovery ranging from 100.66 to 103.90 %. The extraction efficiency of IL-IRAE was proved to be increased by 25 % compared with conventional heat reflux extraction (HRE), ultrasound-assisted extraction (UAE), and microwave-assisted extraction (MAE) methods under the operational parameters investigated in the study, indicating that the developed IL-IRAE method is environmentally friendly, simple, low cost, and efficient, offering great promise for quick determination of active compounds in TCMs and natural plants.
Co-reporter:Jin Ling, Yingjia Yu, Jianan Feng, Changjiang Xu, Jiebing Jiang, Liping Wang, Jiakun Long, Yan Li, Gengli Duan
Journal of Chromatography B 2017 Volume 1054(Volume 1054) pp:
Publication Date(Web):1 June 2017
DOI:10.1016/j.jchromb.2017.04.004
In the present study, a novel sample preparation method based on magnetic core-mesoporous shell microspheres with C8-modified interior pore walls (C8-Fe3O4@mSiO2) was established for the identification of 20(S)-protopanaxadiol (PPD) metabolites in rat plasma by UPLC-Q-TOF-MS/MS analysis. C8-Fe3O4@mSiO2 allowed selective extraction of PPD metabolites from rat plasma by excluding macromolecules in the plasma owing to size exclusion effect. Five extraction conditions including the amount of C8-Fe3O4@mSiO2 microspheres used, extraction time, elution solvents, elution volume, and elution time were investigated and optimized. The present method was compared with two conventional sample preparation methods: protein precipitation and C8 solid phase extraction (C8-SPE). Our method provided higher UPLC intensity of result than protein precipitation method. While the resulting intensity of our method and that of C8-SPE were not significantly different, it consumed less processing time (15 min 55 s for C8-Fe3O4@mSiO2, and 27 min 30 s for C8-SPE). Finally, the proposed method was successfully applied in the identification of PPD metabolites in vivo, in which a total of 17 metabolites and the parent drug were identified in rat plasma.
Co-reporter:Renping Wang, Xueqin Gu, Weiquan Dai, Jun Ye, Feng Lu, Yifeng Chai, Guorong Fan, Frank J. Gonzalez, Gengli Duan and Yunpeng Qi
Molecular BioSystems 2016 vol. 12(Issue 5) pp:1436-1444
Publication Date(Web):11 Mar 2016
DOI:10.1039/C5MB00864F
Celastrol is well known for its anti-inflammatory and anti-cancer effects. In this study, the efficacy of celastrol against dextran sulfate sodium (DSS)-induced inflammatory bowel disease (IBD) in mice was established and the mechanism was investigated using lipidomics. Celastrol treatment significantly alleviated DSS-induced colitis in mice, as revealed by the body weight, colon length, scores of rectal bleeding and diarrhea, serum TNF-α level, and histological analysis results. Lipidomics analysis based on UPLC/MS revealed characteristic changes in the metabolic profiles of the colitis mice, with altered levels of lipid markers associated with IBD, including LPC18:0, LPC18:1, LPC18:2, sphingomyelin (SM), and increased LPC18:0/LPC18:1 and LPC18:0/LPC18:2 ratios. For the celastrol-treated colitis mice, however, levels of the above lipid markers were restored, together with recovered saturated LPC/unsaturated LPC ratios. Accordingly, using GC–MS analysis, increased stearic acid (C18:0)/oleic acid (C18:1) and stearic acid (C18:0)/linoleic acid (C18:2) ratios were observed in colitis mice, which were later recovered after celastrol treatment. Quantitative real-time PCR analysis revealed that the liver expression of stearoyl-coenzyme A desaturase 1 (SCD1), the key enzyme controlling the desaturation of saturated fatty acid, was dramatically inhibited in IBD mice, and was obviously recovered after celastrol treatment. These results suggest that the increased saturated LPC/unsaturated LPC (and saturated fatty acid/unsaturated fatty acid) ratios associated with SCD1 down-regulation could be regarded as biomarkers of colitis, and celastrol alleviates DSS-induced colitis partially via up-regulation of SCD1, restoring the altered balance between stearic acid- and oleic acid-derived lipid species, which plays an important role in alleviating colitis. In all, this study provided the scientific basis for further development of celastrol in treating IBD.
Co-reporter:Jin Ling, Yingjia Yu, Jiajun Zhu, Yan Li, Li Ling, Liping Wang, Changjiang Xu, Gengli Duan
Journal of Chromatography B 2016 Volume 1031() pp:214-220
Publication Date(Web):15 September 2016
DOI:10.1016/j.jchromb.2016.07.044
•We established an HPLC–MS/MS method for quantification of protopanaxadiol in human plasma.•The lower limit of quantification is 0.05 ng/mL and the limit of determination is 0.01 ng/mL.•The method was successfully applied to phase IIa clinical trial of protopanaxadiol capsule.•The measured plasma protopanaxadiol concentration is linearly related to the oral dosage.•Measurements help to detect and prevent errors in the results of clinical trial.A highly sensitive HPLC–MS/MS assay method was established to quantify 20(S)-protopanaxadiol (PPD) in human plasma with dexamethasone as an internal standard. The electrospray ion mass spectrometry (ESI–MS) was operated under the multiple reactions monitoring mode (MRM) using positive ion mode. PPD was extracted from 500 μL plasma samples by liquid–liquid extraction then separated by a C18 analytical column with gradient elution. The concentration of PPD could be determined by this HPLC–MS/MS method over the range of 0.05–20 ng/mL with the lower limit of quantification (LLOQ) of 0.05 ng/mL. The method was successfully applied to phase IIa clinical trial of Yuxintine (PPD capsule) in which plasma samples of 87 subjects were analyzed following 6 weeks of oral administration of placebo or PPD capsules in 5 different doses. In this study, the measured concentration was linearly related to the oral dosage with R = 0.9901. The minimum and maximum values of measured concentration were 0.06 and 11.60 ng/mL, respectively. In addition, plasma concentrations of PPD in depression patients were reported for the first time in our study.
Co-reporter:Chen Xu, Jiajun Zhu, Yan Li, Yingjia Yu and Gengli Duan
RSC Advances 2015 vol. 5(Issue 17) pp:13192-13199
Publication Date(Web):09 Jan 2015
DOI:10.1039/C4RA16040A
As a large group of stable existing organofluorine compounds widely present in the environment, perfluorochemicals (PFCs) could pose potential adverse effects on human health. In this study, a selective and sensitive fluorous solid-phase extraction (F-SPE) method coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed and validated for quantitative analysis of PFCs. The novel fluorous solid-phase cartridges used in the present work were synthesized, which have a fluorous solid phase being typically silica gel with a fluorocarbon bonded phase (–SiMe2(CH2)2C8F17). As a result of the fluorous–fluorous interaction, F-SPE displayed excellent extraction efficiency for the PFCs, including perfluorohexanoic acid (PFHxA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDA). The method contains 4 steps: preconditioning, sample loading, fluorophobic washing and fluorophilic elution. Meanwhile, the cartridges could be regenerated by thorough washing with tetrahydrofuran (THF) and reused multiple times. The analytes collected from F-SPE were redissolved and injected into the LC-MS/MS system for quantitation afterwards. The separation was performed in negative ion mode using multiple reaction monitoring mode on a Shiseido C18 column (150 × 4.6 mm, 5.0 μm) using methanol and buffer (2 mM ammonium acetate, 0.05% HAc) as mobile phases with a gradient of 80/20 (v/v). The four kinds of PFCs could be eluted within 13 min with analytical recoveries being in the range of 95.3–102.8%. The developed method was applied to determine the concentration of PFCs in tap/river/waste samples collected in Shanghai, China which indicates the prospective value of F-SPE for environmental monitoring and protection.
Co-reporter:Fajie Li, Yingjia Yu, Haiying Zhang, Tingting Liu, Yan Li and Gengli Duan
Analytical Methods 2013 vol. 5(Issue 15) pp:3747-3753
Publication Date(Web):03 May 2013
DOI:10.1039/C3AY40135A
The extraction of picroside I and picroside II from Picrorhiza scrophulariiflora Pennell using non-ionic surfactants with the assistance of infrared was investigated and the conditions for maximum yield were determined. Under optimum conditions, i.e. 10% Genapol X-080 (v/v), liquid:solid ratio of 150:1 (mL g−1), infrared power 200 W and infrared-assisted extraction for 4 min, the extraction yield reached the highest value. For the preconcentration of picroside I and picroside II by cloud-point extraction, the solution was incubated in a thermostatic water bath at 100 °C for 10 min, and 15% NaCl (w/v) was added to the solution to facilitate the phase separation. When compared with various polar and nonpolar solvents (pure water, ethanol, acetone, acetic ether and hexane), the extraction efficiency of 10% Genapol X-080 reached a statistically higher value (p < 0.05). By using an infrared-assisted non-ionic surfactant extraction method, the determined amounts of the picrosides in Picrorhiza scrophulariiflora Pennell were statistically higher than those extracted with conventional ultrasound-assisted extraction and heat-reflux extraction (p < 0.05). The results show that infrared-assisted non-ionic surfactant extraction is a good, efficient and green analytical preparatory technique for the rapid extraction and pre-concentration of pharmacologically active ingredients from Picrorhiza scrophulariiflora Pennell without disturbing the subsequent chromatographic analysis.
Co-reporter:Feng Lu, Xinxin Weng, Yifeng Chai, Yongjian Yang, Yinjia Yu, Gengli Duan
Chemometrics and Intelligent Laboratory Systems 2013 Volume 127() pp:63-69
Publication Date(Web):15 August 2013
DOI:10.1016/j.chemolab.2013.06.001
•A novel identification system for screening of the counterfeit drugs is proposed.•The strategy provides an alternative.•The strategy is demonstrated with high rapidity, accuracy and cost-effectiveness.Quick inspection methods for counterfeit drugs are of vital necessity. In this study, the feasibility of portable Raman spectroscopy as an analytical method together with a novel identification system for fake drugs detection is demonstrated. The rapid and convenient identification system based on modified local straight-line screening (LSLS) and principal component analysis (PCA) is developed to distinguish counterfeit from authentic. LSLS algorithm was originally designed to detect synthetic drug(s) adulterated in herbal medicines based on infrared spectroscopy. In order to adapt the LSLS method for the detection of the suspected counterfeit drugs based on portable Raman spectroscopy, modification of weighting is made in this paper to obtain the low false positive rate (FPR) and low false negative rate (FNR). The proposed identification system has been benchmarked by 7 kinds (40 batches) of hypoglycemic tablets and 12 common pharmaceutical excipients. The total sensitivity, specificity and accuracy are 96.77%, 97.48% and 96.35% respectively. The results indicate that the identification system is appropriate for the on-site preliminary screening of the suspected counterfeit drugs.
Co-reporter:Xiaodan Liu, Yingjia Yu, Yan Li, Suli Ning, Tingting Liu, Fajie Li, Gengli Duan
Talanta 2013 Volume 106() pp:321-327
Publication Date(Web):15 March 2013
DOI:10.1016/j.talanta.2012.11.015
In this study, a novel enrichment technique based on magnetic core-mesoporous shell microspheres with C8-modified interior pore-walls (C8-Fe3O4@mSiO2) was successfully developed for the determination of diazepam in rat plasma by LC-MS. Due to the unique properties of the synthesized C8-Fe3O4@mSiO2 microspheres (C8-modified magnetic mesoporous microsphere), small drug molecules like diazepam can enter the mesopore channels and be efficiently absorbed through hydrophobic interaction by interior C8-groups (Octyl functional groups). Large molecules like proteins are excluded from the mesopore channels as a result of size exclusion effect, leading to direct extraction of drug molecules from protein-rich biosmaples such as plasma without any other pretreatment procedure. Moreover, diazepam adsorbed C8-Fe3O4@mSiO2 microspheres could be simply and rapidly isolated through placing a magnet on the bottom of container, and then diazepam could be easily eluted from C8-Fe3O4@mSiO2 microspheres for further LC-MS analysis. Extraction conditions such as amounts of C8-Fe3O4@mSiO2 microspheres added, adsorption time, elution solvent and elution time were investigated. Method validations including linear range, the limit of detection, precision, and recovery were also studied. The results indicated that the proposed method based on C8-Fe3O4@mSiO2 microspheres was simple and accurate for the analysis of diazepam in the rat plasma. And it will provide new ideas for analyzing plasma concentration and pharmacokinetics of similar drugs.Highlights► An enrichment technique based on C8-Fe3O4@mSiO2 microspheres was developed. ► Mesopores on the surface of the microspheres exclude proteins from the sample. ► The C8 groups modified on the inner walls extract drug molecules from the sample. ► The strong magnetic behavior of the microspheres ensure a fast and easy separation.
Co-reporter:Fa-jie Li;Su-li Ning;Yan Li;Ying-jia Yu;Ci-dan Shen;Geng-li Duan
Phytochemical Analysis 2012 Volume 23( Issue 4) pp:292-298
Publication Date(Web):
DOI:10.1002/pca.1357
ABSTRACT
Introduction
Rutin, one of main constituents in Flos Sophorae Immaturus, has been proven to possess several pharmacological properties such as anti-oxidant, anti-platelet, anti-inflammatory effects and so on. However, optimisation of the extraction of rutin from Flos Sophorae Immaturus has rarely been reported. Thus, it is important to develop an effective method to obtain maximum yields of rutin from Flos Sophorae Immaturus.
Objective
To develop an infrared-assisted extraction method for maximum rutin yield from crude Flos Sophorae Immaturus using response surface methodology and HPLC analysis.
Methodology
Through single factor experiments, ranges of the main variables (including methanol concentration, liquid:solid ratio, extraction time and infrared power) affecting the extraction yield of rutin were confirmed. A Box–Behnken design consisting of 24 experimental runs and five replicates at zero point was then applied and a regression model was obtained to predict the optimal extraction yield.
Results
The ANOVA analysis indicated that the regression equation fits very well with the actual situation. The optimal conditions were as follows: infrared power 204.90 W, liquid:solid ratio 30.00 mL/g, methanol concentration 70.00% and extraction time 4.80 min. Under optimal conditions the predicted maximum yield (125.70 mg rutin/0.5 g raw material) was consistent with the experimental value (126.32 ± 0.67 mg rutin/0.5 g raw material) (n = 3).
Conclusion
The application of response surface methodology was reliable and feasible in the optimisation of infrared-assisted extraction of rutin from crude Flos Sophorae Immaturus. Copyright © 2011 John Wiley & Sons, Ltd.
Co-reporter:Yingjia Yu, Bin Chen, Cidan Shen, Yi Cai, Meifen Xie, Wei Zhou, Yile Chen, Yan Li, Gengli Duan
Journal of Chromatography A 2010 Volume 1217(Issue 32) pp:5158-5164
Publication Date(Web):6 August 2010
DOI:10.1016/j.chroma.2010.06.009
This paper proposed a multiple headspace single-drop microextraction (MHS-SDME) method coupled to gas chromatography with flame-ionization detection (GC-FID) for direct determination of residual solvents in solid drug product. The MHS-SDME technique is based on extrapolation to an exhaustive extraction of consecutive extractions from the same sample which eliminates the matrix effect on the quantitative analysis of solid samples. The total peak area of analyte is calculated with a beta constant which can be obtained from the slope of the linear regression that related to the peak area of each extraction and the number of extraction times. In this work, a model drug powder was chosen and the amounts of residues of two solvents, methanol and ethanol, were investigated. The factors influencing the extraction process including extraction solvent, microdrop volume, extraction time, sample amount, thermostatting temperature and incubation time were studied. 10 mg of drug powder was incubated for 3 h at 140 °C prior to the first extraction and thermostatted for 15 min at 140 °C between each extraction. Extraction was carried out with 2 μL of dimethyl sulfoxide (DMSO) as the microdrop for 5 min. The features of the method were established using standard solutions. Validation of the proposed method showed good agreement with the traditional dissolution method for analysis of residual solvents in drug product. The results indicated that MHS-SDME has a great potential for the quantitative determination of residual solvents directly from the solid drug products due to its low cost, ease of operation, sensitivity, reliability and environmental protection.
Co-reporter:Tao Zhou;Haiying Zhang
Journal of Separation Science 2007 Volume 30(Issue 16) pp:2620-2627
Publication Date(Web):20 SEP 2007
DOI:10.1002/jssc.200700097
A simple and reliable HPLC method was developed for the simultaneous quantitative analysis of diethylene glycol (DEG) and propylene glycol (PG) in pharmaceutical products by precolumn derivatization. The derivatization reagent p-toluenesulfonyl isocyanate (TSIC, 10 μL, 20% in ACN v/v) was added to 100 μL of the sample, and then 10 μL of water was added. The resulting derivatives were separated using a C18 analytical column and a mobile phase composed of 0.01 M KH2PO4 buffer (adjusted to pH 2.5 with phosphoric acid) and ACN (47:53 v/v) at 1 mL/min and 25°C. For detection, UV light at 227 nm was used. The derivatization conditions including reaction time, temperature, and concentration of TSIC were optimized. The calibration curves were linear from 0.062 to 18.6 μg/mL (r2 = 0.9999) and from 0.071 to 21.3 μg/mL (r2 = 0.9999) for DEG and PG, respectively. The RSD values of intra- and interday assays were all below 4% for DEG and PG. The proposed method was then successfully applied to analyze two Armillarisin A injection samples and two spiked syrup samples.
Co-reporter:Tao-min Huang;Hai-Ying Zhang;Nian-zhu Chen;Chun-Hui Deng;Zhen Liu
Chromatographia 2007 Volume 65( Issue 1-2) pp:111-114
Publication Date(Web):2007 January
DOI:10.1365/s10337-006-0124-3
A rapid, simple, and sensitive HPLC method with UV detection is described for determination of the active components, peptides, in Lu-Ying-Ke-Li, a Chinese traditional patent medicine. Oxytocin was selected for quantification. Effective chromatographic separation was achieved on a C18 column. The detection wavelength was 220 nm. The calibration plot for oxytocin was linear in the range 5–400 μg mL−1; the regression coefficient was 0.9999. The limit of quantification for oxytocin was 100 ng. It is suggested the method can be used for routine quality control of Lu-Ying-Ke-Li.
Co-reporter:Yingjia Yu;Bei Yang;Tao Zhou;Haiying Zhang;Luping Shao
Annali di Chimica 2007 Volume 97(Issue 10) pp:
Publication Date(Web):4 SEP 2007
DOI:10.1002/adic.200790091
In this paper, microwave distillation and solid-phase microextraction coupled with gas chromatography-mass spectrometry (MD-SPME/GC-MS) was developed for the analysis of essential components in safflower. Using the MD-SPME technique, the isolation, extraction and concentration of volatile compounds in safflower were carried out in only one step. Some parameters affecting the extraction efficiency such as SPME fiber coating, microwave power, irradiation time and the volume of water added were optimized. The optimal experiment parameters obtained were: 65 μm CW/DVB SPME fiber, a microwave power of 400 W, an irradiation time of 3 min and water volume of 1 mL. The proposed method has been compared with conventional steam distillation (SD) for extraction of essential oil compounds in safflower. Using MD-SPME followed by GC-MS, 32 compounds in safflower were separated and identified, which mainly included paeonol, alpha-asarone, beta-asarone, 1-methyl-4-(2-propenyl)-benzene and diethenyl-benzene, whereas only 18 compounds were separated and identified by conventional SD followed by GC-MS. The relative standard deviation (R.S.D.) values of less than 10 % show that the proposed method has good reproducibility. The results show that MD-SPME/GC-MS is a simple, rapid, effective method for the analysis of volatile oil components in safflower.
Co-reporter:Chun-Hui Deng;Tao-min Huang;Zhen Liu;Nian-zhu Chen;Geng-Li Duan
Journal of Separation Science 2006 Volume 29(Issue 15) pp:2296-2302
Publication Date(Web):6 SEP 2006
DOI:10.1002/jssc.200600162
In this study, we developed a simple, rapid, sensitive, and reliable method for the determination of glucosamine sulfate in human plasma, which was based on derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl) followed by reverse-phase HPLC-FLD. For the first time, FMOC-Cl was introduced into derivatization of glucosamine sulfate in human plasma. The amino groups of glucosamine sulfate and vertilmicin sulfate (the internal standard) were trapped with FMOC-Cl to form glucosamine-FMOC-Cl and vertilmicin-FMOC-Cl adducts, which can be very suitable for HPLC-FLD. Precipitation of plasma proteins by acetonitrile was followed by vortex mixing and centrifugation. Chromatographic separation was performed on a C18 column (DIAMONSIL 150×4 mm id, 5 μm) with a mobile phase gradient consisting of acetonitrile and water at a flow-rate of 1 mL/min. The retention times of glucosamine-FMOC-Cl and vertilmicin-FMOC-Cl adducts were 8.9 and 21.2 min, respectively. This method was shown to be selective and sensitive for glucosamine sulfate. The limit of detection was 15 ng/mL for glucosamine sulfate in plasma and the linear range was 0.1–10 mg/mL in plasma with a correlation coefficient (r) of 0.9999. The relative standard deviations (RSDs) of intra-day and inter-day assays were 5.2–8.1% and 6.1–8.5%, respectively. Extraction recoveries of glucosamine sulfate in plasma were greater than 90%. The validated method was successfully applied to the determination of glucosamine sulfate in human plasma samples.
Co-reporter:Gengli Duan;Chunhui Deng;Yunqiu Yu;Lei Cai;Bei Yang
Journal of Separation Science 2006 Volume 29(Issue 14) pp:2173-2178
Publication Date(Web):1 SEP 2006
DOI:10.1002/jssc.200600085
An LC-ESI-MS method was developed and validated for the assay of apomorphine in canine plasma using one-step liquid–liquid extraction. The analytes were separated on a Phenomenex Gemini C18 (150 mm×2.0 mm id 3 μm) column and determined by MS in the positive ion mode. The linear range was 0.4–40 ng/mL with an LOD of 0.2 ng/mL for apomorphine in plasma. The intraday and interday precision and accuracy of quality control samples were < 5.9% RSD and < 7.5% bias for apomorphine. Extraction recoveries were > 80%. The validated method was successfully applied to analyze canine plasma samples in a pharmacokinetic study of apomorphine in dogs and detailed pharmacokinetic parameters were calculated.
Co-reporter:Y.F. Sha, S. Shen, G.L. Duan
Journal of Pharmaceutical and Biomedical Analysis 2005 Volume 37(Issue 1) pp:143-147
Publication Date(Web):7 February 2005
DOI:10.1016/j.jpba.2004.09.050
A simple, rapid and sensitive method for determination of tramadol in plasma samples was developed using headspace solid-phase microextraction (HS-SPME) and gas chromatography with mass spectrometry (GC–MS). The optimum conditions for the SPME procedure were: headspace extraction on a 65-μm polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber; 0.5 mL of plasma modified with 0.5 mL of sodium hydroxide (0.1 M); extraction temperature of 100 °C, with stirring at 2000 rpm for 30 min. The calibration curve showed linearity in the range of 1–400 ng mL−1 with regression coefficient corresponding to 0.9986 and coefficient of the variation of the points of the calibration curve lower than 10%. The detection limit for tramadol in plasma was 0.2 ng mL−1. The proposed method was successfully applied to determination of tramadol in human plasma samples from 10 healthy volunteers after a single oral administration.
Co-reporter:Ming Zuo, Ming-jie Gao, Zhen Liu, Lei Cai, Geng-Li Duan
Journal of Chromatography B 2005 Volume 814(Issue 2) pp:331-337
Publication Date(Web):25 January 2005
DOI:10.1016/j.jchromb.2004.10.054
In this paper, p-toluenesulfonyl isocyanate has been reported as a novel derivatization reagent with strong nuclephilic reactivity for the hydroxyl compounds. The derivatization for the two pharmacologically active 3-hydroxyl metabolites, 3α-hydroxyl-7-methyl-norethynodrel and 3β-hydroxyl-7-methyl-norethynodrel by p-toluenesulfonyl isocyanate can be accomplished in 2 min under room temperature. The offline derivatization procedure introduced an easily ionizable sulfonylcarbamic ester moiety to the metabolites. This greatly improved the analyte's sensitivity in negative electrospray ionization and enabled us to achieve the desired lower limit of quantitation at 100 pg/ml in plasma. Therefore, a sensitive high performance liquid chromatography-mass spectrometry (HPLC–MS) method for the analysis of the two stereo isomers was developed. The method had been validated to be accurate, precise, and sensitive, and can be used for the metabolism pharmacokinetic study of tibolone in human subjects.
Co-reporter:Yunfei Sha, Chunhui Deng, Zhen Liu, Taomin Huang, Bei Yang, Gengli Duan
Journal of Chromatography B 2004 Volume 806(Issue 2) pp:271-276
Publication Date(Web):5 July 2004
DOI:10.1016/j.jchromb.2004.04.006
A simple, rapid and sensitive method for determination of rivastigmine in plasma samples was developed using headspace solid-phase microextraction (HS-SPME) and gas chromatography with mass spectrometry (GC–MS). The optimum conditions for the SPME procedure were: headspace extraction on a 65-μm polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber; 0.5 ml of plasma modified with 1.0 ml of sodium hydroxide-sodium carbonate solution (0.7 M:0.5 M); extraction temperature of 100 °C, with stirring at 2000 rpm for 30 min. The calibration curve showed linearity in the range from 0.2 to 80 ng/ml with regression coefficient corresponding to 0.9965 and coefficient of the variation of the points of the calibration curve lower than 10%. The quantification limit for rivastigmine in plasma was 0.2 ng/ml. The method was applied to determination of rivastigmine in canine plasma samples from animals after a single oral administration.
Co-reporter:
Analytical Methods (2009-Present) 2013 - vol. 5(Issue 15) pp:
Publication Date(Web):
DOI:10.1039/C3AY40135A
The extraction of picroside I and picroside II from Picrorhiza scrophulariiflora Pennell using non-ionic surfactants with the assistance of infrared was investigated and the conditions for maximum yield were determined. Under optimum conditions, i.e. 10% Genapol X-080 (v/v), liquid:solid ratio of 150:1 (mL g−1), infrared power 200 W and infrared-assisted extraction for 4 min, the extraction yield reached the highest value. For the preconcentration of picroside I and picroside II by cloud-point extraction, the solution was incubated in a thermostatic water bath at 100 °C for 10 min, and 15% NaCl (w/v) was added to the solution to facilitate the phase separation. When compared with various polar and nonpolar solvents (pure water, ethanol, acetone, acetic ether and hexane), the extraction efficiency of 10% Genapol X-080 reached a statistically higher value (p < 0.05). By using an infrared-assisted non-ionic surfactant extraction method, the determined amounts of the picrosides in Picrorhiza scrophulariiflora Pennell were statistically higher than those extracted with conventional ultrasound-assisted extraction and heat-reflux extraction (p < 0.05). The results show that infrared-assisted non-ionic surfactant extraction is a good, efficient and green analytical preparatory technique for the rapid extraction and pre-concentration of pharmacologically active ingredients from Picrorhiza scrophulariiflora Pennell without disturbing the subsequent chromatographic analysis.
