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Shen J.,China Agricultural University | Wang W.,Beijing WDWK Biotechnological Corporation Ltd | Xia X.,China Agricultural University | Zhu J.,China Agricultural University | And 8 more authors.
Analytical Letters | Year: 2013

A pretreatment method was developed for the determination of four nitrofuran metabolites and chloramphenicol in pork, chicken, fish, and shrimp. Homogenized samples were hydrolyzed and derivatized with 2-nitrobenzaldehyde. Extraction was performed using ethyl acetate followed by purification of the extract by hexane. Lastly, the ethyl acetate was dried under nitrogen and the residue was redissolved for analysis. The performance of the method was satisfactory for all drugs tested at contamination levels close to or below the relevant European Union maximum levels permitted. The limits of detection (LODs) of the method were 0.025-0.13 ng/g. Recoveries higher than 72.0% were obtained for all drugs tested, and the coefficient of variation was less than 15%. Results from analysis of unknown samples by the developed ELISA were similar to those obtained by a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. © 2013 Copyright Taylor and Francis Group, LLC.

Pei X.,China Agricultural University | Wang Q.,China Agricultural University | Li X.,Beijing WDWK Biotechnological Co. | Xie J.,China Agricultural University | And 5 more authors.
Food Analytical Methods | Year: 2015

Olaquindox (OLA), used as a medicinal feed additive, has been put under ban due to hazard concerns over animal-derived food security. In this study, a simple, rapid, ultrasensitive, and quantitative gold immunochromatography assay (GICA) was established to analyze OLA in animal feed samples and surface water samples to monitor food security. Various trying has been experimented to improve the sensitivity. The IC50 of the optimized method is 3.35 μg L−1 for feedstuff and 0.35 μg L−1 for environmental water. The recoveries ranged from 77.33 to 86.91 % (CV <23.62 %) for spiked feedstuff and 96.30 to 117.83 % (CV <22.51 %) for spiked water samples. Then, the developed GICA was applied to animal feed and field water, followed by confirmation with ELISA and the consistency of results indicated that the developed GICA could be applied for rapid screening of OLA in real samples. Compared with previous assay, the developed GICA in this study was more sensitive and more rapid, which exhibited broader prospect to supervise the animal products and water rapidly. [Figure not available: see fulltext.] © 2015 Springer Science+Business Media New York

Zhou J.,China Agricultural University | Zhu K.,Ludwig Maximilians University of Munich | Xu F.,Chinese Academy of Agricultural Sciences | Wang W.,Beijing WDWK Biotechnological Company | And 3 more authors.
Journal of Agricultural and Food Chemistry | Year: 2014

The residue of lincomycin (LIN) in edible animal foodstuffs caused by the widespread use of veterinary drugs is in need of rapid, simple, and sensitive detection methods. The present work introduces a fluorescent microsphere immunoassay (FMIA) for detecting LIN in different samples based on the competitive immunoreaction on the chromatography test strip. The residues of LIN in different samples compete with bovine serum albumin (BSA) labeled LIN conjugates on the T-line to bind to the anti-LIN monoclonal antibody labeled fluorescent microspheres (FM-mAbs). Captured FM-mAbs on the T-line represent the fluorescent intensity, which is detected under UV light and quantified by a fluorescent reader. Under optimized conditions, the dynamic range is from 1.35 to 3.57 ng/mL, and the 50% inhibition concentration (IC50) is 2.20 ng/mL. This method has 4.4% cross-reactivity with clindamycin and negligible cross-reactivity (<0.1%) with other analogues. To reduce the matrix effects, a dilution method is used to pretreat the samples, and the recoveries range from 73.92 to 120.50% with coefficient of variations <21.76%. In comparison with the results of ELISA and colloidal gold immunoassay, FMIA has obvious advantages such as easy operation, time savings, high sensitivity and specificity, and broader prospect. © 2014 American Chemical Society.

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