A new analytical method for the determination of cinchona alkaloids by flow-injection sampling and chemiluminescence (CL) detection is developed. A weak CL can be emitted by oxidation reaction of cinchona alkaloid with potassium permanganate. The conditions for CL emission were investigated and optimized. The linear range of 1.0 × 10−7 – 8.0 × 10−5 g mL−1 was obtained for quinine, quinidine and cinchonine. The detection limit was 3.2 × 10−8 g mL−1 for quinine and 3.0 × 10−8 g mL−1 for quinidine and cinchonine. The recoveries of the three drugs from urine and serum samples were in the range of 95.0–105% with RSDs of 1.7–2.0%. The proposed method was used for the determination of cinchona alkaloids in pharmaceuticals and biological fluids with satisfactory result. The possible CL mechanism is also discussed.

Novel chemiluminescence (CL) reaction systems were established for the determination of anticancer drugs, including adriamycin (ADM), hydroxycamptothecin (HCPT), mitomycin (MMC), and fluorouracil (5-FU). The formaldehyde-sensitized CL emission mechanism was developed for four systems by comparing the fluorescence emission and CL spectra. For ADM-KMnO4-HNO3, HCPT-KMnO4-H2SO4, MMC-KMnO4-HNO3, and 5-FU-KMnO4-HCl systems, the illuminant was a singlet state bimolecule oxygen, 1O21O2(1Δg1Δg), which was formed from 1O2 (1Δg) produced in the reaction system. The illuminant emits CL spectra at 539 or 549 nm. The presence of formaldehyde can sensitize CL emission because it may accelerate the generation of 1O2 (1Δg). The optimum conditions for the CL emission were chosen. The relationships between the relative CL intensity and the concentration of the studied analytes are linear with the correlation coefficients in the range of 0.9959–0.9989. The proposed four enhanced CL systems provide a good linearity, a high sensitivity, precision, and the potential capability for the determination of anticancer drugs in biological samples.

A novel chemiluminescence (CL) method was established for two anticancer drugs, adriamycin (ADM) and mitomycin (MMC), based on potassium permanganate oxidation in the presence of formaldehyde. The sensitized CL emission mechanism was developed by comparing the fluorescence emission with CL spectra. Illuminant was the singlet state bi-molecule oxygen, 1O21O2 (1Δg1Δg), from 1O2 (1Δg) which was produced in the reaction system, and emitted CL spectra at 639 nm or 649 nm. The presence of formaldehyde may accelerate the generation of 1O2 (1Δg) and sensitized CL emission. The optimum conditions for CL emission were investigated and optimized. The relationships between the relative CL intensity and the concentration of the studied analytes found to be linear. The detection limit was 3 × 10−8 g ml−1 for ADM and 3 × 10−9 g ml−1 for MMC. The relative standard deviations are 2.2% and 1.8% for determinations of ADM at 2.0 × 10−6 g ml−1 and MMC at 2.0 × 10−7 g ml−1, respectively. The proposed sensitized CL system was successfully applied to the determination of ADM and MMC in their injections with satisfactory results.

An accurate method based on the use of gel permeation chromatography (GPC)–liquid chromatography–tandem mass spectrometry interfaced with electrospray ionization (GPC–LC–ESI-MS/MS) was devised for the simultaneous determination of Sudan (I–IV), Sudan Orange G, Sudan Red B, Sudan Red G, Sudan Red 7B, Butter Yellow and Para Red in hot chili products. A GPC clean-up procedure was developed for simultaneous quantification of 10 dyes in hot chili and hot chili products avoiding some interference and permitting multiple injections without damaging the column. A HPLC was performed on an Inertsil C18 column using a multistep gradient elution with 0.1% formic acid and methanol as the mobile phase. Mass spectral acquisition was done in positive ion mode. Linearity of around three orders in the magnitude of concentration was generally obtained with the correlation coefficients (r2) of 0.9984–0.9997. Limit of detection (LOD) and limit of quantification (LOQ) for the investigated dyes were in the ranges of 0.1–1.8 and 0.4–5.0 μg/kg depending on matrices, respectively. The recoveries of the 10 synthetic dyes in five matrices ranged from 81.7 to 92.9%. The intra- and inter-day precision (RSDs) was between 2.9–7.8 and 3.9–8.1%, respectively. This method has been applied successfully for the determination of the studied 10 banned dyes in hot chili products.

A method was developed for the determination of the seven nitroimidazoles including metronidazole (MNZ), ronidazole (RNZ), dimetridazole (DMZ), tinidazole (TNZ), ornidazole (ONZ), secnidazole (SNZ) and the common metabolite of RNZ and hydroxydimetridazole (DMOHZ) in poultry and pork muscles by high-performance liquid chromatography (HPLC) with ultraviolet detection (UV). After extraction with ethyl acetate and evaporation, the nitroimidazoles were redissolved in ethyl acetate and purified using strong cation exchange (SCX) solid-phase extraction (SPE) column. The HPLC separation was carried through on a C18 bonded silica column with a deionized water–methanol–acetonitrile mobile phase using a gradient elution procedure. The limit of detection of all the seven nitroimidazoles was 0.2 μg/kg. The recoveries of the seven nitroimidazoles for chicken, pork and bacon samples spiked with 1–20 μg/kg were in the range of 71.4–99.5%. The linearity is satisfactory with a correlation coefficient of >0.998 at concentrations ranging from 0.7 to 60 μg/kg. The relative standard deviations of 10 measurements for spiked chicken, pork and bacon samples at the concentration of 1 and 20 μg/kg were in the range of 6.2–13.9% and 4.0–8.7%, respectively. The intra-day precision (n = 5) for nitroimidazoles residues in chicken spiked at 20 μg/kg is 6.9%, and the inter-day precision for 5 days (n = 25) is 11%. The method is capable of identifying nitroimidazole residues at ≥0.7 μg/kg levels and was applied in the determination of nitroimidazole residues in meat sample.

A multiresidue method has been developed for the simultaneous determination of sulfadiazine, sulfathiazole, sulfapyridine, sulfamerazine, sulfamethoxydiazine, sulfamethylthiazole, sulfamethazine, sulfamonomethoxine, sulfamethoxypyridazine, sulfisoxazole, sulfamethoxazole, sulfadimethoxine and sulfaquinoxaline in natural animal casings by HPLC after solid-phase extraction. The sulfonamides were extracted with acetonitrile and the extract cleaned up with an Oasis MCX SPE cartridge prior to analysis. Separation was on a ZOBAX Eclipse XDB-C8 column using gradient elution with acetonitrile/methanol/0.1% acetic acid. The effect of separation conditions on chromatographic behavior and recovery has been studied. Calibration graphs were linear with very good correlation coefficients (r = 0.9983−0.9996) in the concentration range from 0.02 to 1 μg mL−1. The limits of quantitation (LOQ) for the 13 sulfonamides were in the range of 1.5–2.2 μg kg−1. Decision limits (CCα) and detection capabilities (CCβ) were in the range of 105.2–111.0 and 113.0–120.2 μg kg−1, respectively. The recovery for casings spiked with 1.5–100 μg kg−1 ranged from 65.2 to 85.9%. The relative standard deviations (RSDs) of the sulfonamides for six measurements at 100 μg kg−1 were from 2.2 to 7.7%. The applicability of the method to the analysis of salted swine casings, salted sheep casings and dry casing samples was demonstrated.

Theophylline imprinted monolithic columns were designed and prepared for rapid separation of a homologous series of xanthine derivatives, caffeine, and theophylline by an in situ thermal-initiated copolymerization technique. Caffeine and theophylline were fully separated both under isocratic and gradient elutions on this kind of monolithic molecularly imprinted polymers (MIP) column. The broad peak showed in isocratic elution could be improved in gradient elution. Some chromatographic conditions such as mobile phase composition, flow rate, and the temperature on the retention times were investigated. Hydrogen bonding interaction and hydrophobic interaction played an important role in the retention and separation. The binding capacity was evaluated by static adsorption and Scatchard analysis, which showed that the dissociation constant (KD) and the maximum binding capacity (Qmax) were 1.50 mol/L, and 236 μmol/g for high affinity binding site, and 7.97 mol/L and 785 μmol/g for lower affinity binding site, respectively. Thermodynamic data (ΔΔH and ΔΔS) obtained by Van’t Hoff plots revealed an enthalpy-controlled separation. The morphological characteristics of monolithic MIP were investigated by scanning electron microscope, which showed that both mesopores and macropores were formed in the monolith. The present monolithic MIP column was successfully applied for the quantitative determination of caffeine and theophylline in different kinds of green tea.

A new analytical method for the determination of cinchona alkaloids by flow-injection sampling and chemiluminescence (CL) detection is developed. A weak CL can be emitted by oxidation reaction of cinchona alkaloid with potassium permanganate. The conditions for CL emission were investigated and optimized. The linear range of 1.0 × 10−7 – 8.0 × 10−5 g mL−1 was obtained for quinine, quinidine and cinchonine. The detection limit was 3.2 × 10−8 g mL−1 for quinine and 3.0 × 10−8 g mL−1 for quinidine and cinchonine. The recoveries of the three drugs from urine and serum samples were in the range of 95.0–105% with RSDs of 1.7–2.0%. The proposed method was used for the determination of cinchona alkaloids in pharmaceuticals and biological fluids with satisfactory result. The possible CL mechanism is also discussed.