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Hu J.,University of Sichuan | Zeng L.,University of Sichuan | He L.,U.S. Center for Disease Control and Prevention | You F.,U.S. Center for Disease Control and Prevention | And 2 more authors.
Journal of Chromatographic Science | Year: 2016

A reliable method for simultaneous determination of 10 illegal adulterants including chlortalidone, hydrochlorothiazide, indapamide, metoprolol, nifedipine, nimodipine, nitrendipine, reserpine, triamterene and valsartan in antihypertensive functional foods by ultra-high-performance liquid chromatography coupled with electrospray ionization-tandem mass spectrometry is presented in this article. The target chemicals were extracted with acetonitrile ultrasonically and cleaned up using multiwalled carbon nanotubes-dispersive solid-phase extraction. The separation was performed on a Waters ACQUITY UPLC BEH C18 Column (2.1 × 100 mm, 1.7 μm) with acetonitrile, 0.1% formic acid and 10 mmol/L ammonium acetate solution as mobile phase at a flow rate of 0.2 mL/min. Multiple reaction monitoring was applied for detection and sildenafil was used as the internal standard. The correlation coefficients of the method were >0.995, with the limits of detection of 0.022-0.30 ng/mL and the limits of quantification of 0.075-0.99 ng/mL. The interday and intraday relative standard deviations were <9.77% and the recoveries were in the range of 85.8-109%. The established method has been applied for the analysis of real samples, and reserpine was detected in a tonic wine sample with a content of 60.1 ± 3.2 mg/L. © 2016 The Author 2016. Published by Oxford University Press. All rights reserved. Source


Xue Y.,University of Sichuan | Xue Y.,U.S. Center for Disease Control and Prevention | Chen N.,Branch Hospital of Tibetan Office in Chengdu | Luo C.,U.S. Center for Disease Control and Prevention | And 3 more authors.
Analytical Methods | Year: 2013

A simple, rapid, inexpensive and efficient method based on dispersive liquid-liquid microextraction (DLLME) coupled with high performance capillary electrophoresis (HPCE) has been developed for the extraction and determination of methylparaben (MP), ethylparaben (EP), propylparaben (PP), butylparaben (BP), sorbic acid (SOA), benzoic acid (BA), and salicylic acid (SA) in cosmetic products. A dispersive solution composed of 50 μL trichloromethane and 0.45 mL isopropyl alcohol was used to extract the target analytes from acidified sample solution quantitatively in the DLLME procedure. A suitable amount of lower layer was transferred into a vial and evaporated to dryness under nitrogen gas. The residue was reconstituted in methanol-water (20:80, v/v) solution, and separated using bare fused-silica capillary (50 μm i.d., 50 cm of total length, and 41 cm effective length) and detected at 230 nm. Urobenzoic acid was used as the internal standard. The calibration curves were linear in the range of 0.05 to 5.0 μg mL-1 for MP and SA, and 0.025 to 5.0 μg mL-1 for the rest with the coefficients of correlation ranging from 0.9978 to 0.9995. The limits of detection were in the range of 0.200-0.375 mg kg-1 with enrichment factors ranging from 41 to 133 for all target analytes. Recoveries of the method were in the range of 71.1-112.6%, with the intraday RSDs and interday RSDs in the range of 2.22-4.51% and 3.05-4.89%, respectively. This method has been successfully applied for analysis of the preservatives in different samples of cosmetic. © 2013 The Royal Society of Chemistry. Source


Zeng L.,University of Sichuan | Zeng L.,Provincial Key Laboratory for Food Safety Monitoring and Risk Assessment of Sichuan | Li Y.,University of Sichuan | Li Y.,Provincial Key Laboratory for Food Safety Monitoring and Risk Assessment of Sichuan | And 7 more authors.
Journal of Chromatographic Science | Year: 2015

Consumption of functional foods based on extracts from selected herbs to alleviate hypertension is an increasingly common practice in China. Adulteration of these foods with pharmaceuticals can significantly impact a consumer's health. To control the quality of the functional foods effectively, a method for the simultaneous determination of 10 common adulterants including chlortalidone, hydrochlorothiazide, indapamide, metoprolol, nifedipine, nimodipine, nitrendipine, reserpine, triamterene and valsartan in antihypertensive functional foods was developed. The target chemicals in samples were ultrasonically extracted with acetonitrile, and then cleaned-up with multi-walled carbon natotubes-dispersive solid-phase extraction. Finally, the analytes were separated with a C18 column using binary mobile phases consisting of acetonitrile and 0.03 mol/L KH2PO4 solutions (pH 3.0). The flow rate of the mobile phase was 0.80 mL/min, and the column temperature was 35°C. The detection wavelength was set at 220 nm. The limits of detection and quantification of the method ranged from 0.014 to 0.053 and 0.047 to 0.178 μg/mL, respectively. The recoveries of the method were in the range of 80.1-98.1% with relative standard deviations <9.53%. The method was successfully applied to the determination of the target chemicals in real samples and simulated samples, and respirine was detected in one tonic wine sample with a concentration of 56.8 ± 1.2 mg/L. © The Author 2015. Published by Oxford University Press. Source


Lu D.,University of Sichuan | Yang Y.,University of Sichuan | Wu X.,Jiangxi Provincial Institute for Food and Drug Control | Zeng L.,University of Sichuan | And 4 more authors.
Analytical Methods | Year: 2015

A rapid and efficient gas chromatography-mass spectrometry (GC-MS) has been developed for determination of eight VE isomers including α-, β-, γ-, δ-tocopherols and tocotrienols, as well as α-tocopherol acetate in functional foods and nutritional supplements. The vitamin E isomers in samples were directly extracted without saponification with mixed solvents of methanol and hexane (7 : 3,v/v). Good separation was achieved using a VF-5MS column (30 m × 0.25 mm, 0.25 μm) within 13 min. The mass spectrometer was operated in both full scan mode and SIM mode using electron impact ionization. Qualitative detection was based on characteristic ion pairs and retention time. Dibenzanthracene was used as an internal standard for quantification measurement. The linear ranges of the method were from 0.1 to 40 μg mL-1 with the correlation coefficients greater than 0.997. The detection limits ranged from 0.09 ng mL-1 to 0.46 ng mL-1, and the quantification limits were from 0.29 ng mL-1 to 1.52 ng mL-1. The intra-day and inter-day relative standard deviations (RSDs) of the method (for 1 μg mL-1 standard solution) were in the range of 4.9% to 8.0% and 2.1% to 4.9%, respectively. The average recoveries of the method ranged from 83.2% to 107%, with the RSDs from 1.1% to 8.4%. The method has been applied for the determination of VE isomers and α-tocopherol acetate in functional foods and nutritional supplements with satisfactory results. This journal is © The Royal Society of Chemistry. Source


Zhou C.,Sichuan University | Sun C.,Sichuan University | Sun C.,Provincial Key Laboratory for Food Safety Monitoring and Risk Assessment of Sichuan | Ruan J.,Sichuan University | And 3 more authors.
Analytical Letters | Year: 2015

A duplex polymerase chain reaction (PCR)-capillary electrophoresis-laser induced fluorescence (CE-LIF) method was developed to determine Yersinia enterocolitica in food sensitively, rapidly, and reliably. Two sets of primers were selected to amplify the genus-specific 16 S ribosomal RNA gene and ail gene associated with the pathogenicity of Yersinia enterocolitica. The parameters of duplex PCR and the conditions for CE-LIF were optimized. Under the optimum conditions, the PCR products of Yersinia enterocolitica were determined within twenty minutes. Alignment analysis showed favorable agreement with published sequences from GenBank, indicating that the primers were specific and the PCR results were reliable. The method detected 16 colony forming units per milliliter pathogenic Yersinia enterocolitica. The intraday precision of migration time of the DNA marker and the PCR products were between 1.13 and 1.81 percent. In summary, a new method combining duplex PCR and CE-LIF is reported for specific, sensitive, and reproducible detection of Yersinia enterocolitica in food with low sample consumption and cost. © 2015, Copyright © Taylor & Francis Group, LLC. Source

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