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Wang P.,Nankai University | Yin Y.,Nankai University | Eremin S.A.,Moscow State University | Rybakov V.B.,Moscow State University | And 6 more authors.
Journal of Agricultural and Food Chemistry | Year: 2013

An indirect immunoassay for the determination of vitamin B2 in food samples and vitamin tablets was developed. A carbodiimide-modified active ester method was used to synthesize the immunogen for vitamin B2. The coupling ratio of vitamin B2 to carrier protein in immunogen was 19.98:1. The titer of the polyclonal antibody was 1:64000, and the antibody showed high specificity in the presence of vitamin B2 photolytic products and other B group vitamins. The immunoassay showed detection limits (LODs) of 1.07 ng/mL in PBS, 24.6 ng/g in vitamin drink, and 0.50 mg/kg in milk powder. Recovery was 99.58-110.91% in milk powder and 70.20-100.5% in vitamin drink. Vitamin B2 samples were analyzed by high-pressure liquid chromatography (HPLC) and the immunoassay, and results showed good agreement. Finally, this method was applied to detect vitamin B2 in commercial milk powder and vitamin tablets, and the detected amount correlated well with the labeled amount. © 2013 American Chemical Society.


Song Z.,Nankai University | Wang Y.,Nankai University | Dong Y.,Nankai University | Xu K.,Nankai University | And 7 more authors.
Analytical Methods | Year: 2016

For routine monitoring of the pharmacokinetic behavior of anticancer drug methotrexate (MTX), polyclonal antibodies for MTX were originally produced, and a sensitive chemiluminescence immunoassay (CLIA) was developed for the determination of plasma MTX. Three kinds of coupling reagents (EDC, CDI and isobutyl chloroformate) were utilized to synthesize MTX immunogens. The coupling ratio, titer and sensitivity of polyclonal antibodies for each immunogen were evaluated. Consequently, MTX-EDC-cBSA was found to be the optimal immunogen since it showed the highest coupling ratio and yielded antibodies with the highest sensitivity. Under optimal conditions, the developed CLIA showed a limit of detection (LOD) of 4.3 ng mL-1 in buffer and 9.1 ng mL-1 in plasma with acceptable coefficients of variations (<14.9%). The method exhibited no cross-reaction with the MTX metabolite (7-OH MTX) and structural analogs. When applied in a pharmacokinetic study, the CLIA results were statistically consistent with the HPLC method in measuring key pharmacokinetic parameters (t1/2, Cmax, AUC0-12 and MRT0-12). In conclusion, the CLIA method showed advantages of simple sample preparation, low cost, high sensitivity and good reproducibility. These properties make it a potential tool in the rapid detection of MTX for therapeutic drug monitoring (TDM). © The Royal Society of Chemistry 2016.


Xu Z.,Nankai University | Zheng L.,Nankai University | Yin Y.,Nankai University | Wang J.,Nankai University | And 6 more authors.
Food Control | Year: 2015

An enzyme immunoassay for erythrosine (Ery) in food products was developed in this study. Anti-Ery polyclonal antibody was obtained by immunizing rabbits with Ery-cationized BSA (cBSA) conjugates. Coupling ratios of erythrosine to carrier proteins were measured to be 16.6:1 in immunogen and 13.5:1 in coating antigen. The developed method showed high sensitivity with the IC50 value up to 29.1±6.79ngmL-1. In food samples (healthy energy drink, breezer, grape juice, coca-cola sugar, fermented bean curd and tomato paste), the limit of detection (LOD) values of the developed method ranged from 2.2ngmL-1 to 8.3ngmL-1. The recoveries ranged from 86.3% to 115.5%. Intra-assay and inter-assay variation were lower than 9.6% and 10.7% respectively. The method could specifically recognize Ery among commonly used food colors, and the results obtained with the proposed immunoassay were well related with that of the reference high performance liquid chromatography (R2>0.9999). Therefore, the proposed method could be selectively used for rapid screening Ery in the mentioned foodstuffs. © 2014 Elsevier Ltd.


Zhang B.,Jiangsu University | Du D.,Jiangsu University | Meng M.,Nankai University | Eremin S.A.,Moscow State University | And 4 more authors.
Analytical Letters | Year: 2014

Fluoroquinolones are effective antimicrobial agents, but their residues in food may cause serious health issues. Hence, it is necessary to develop a rapid and simple assay for fluoroquinolones. In this study, monoclonal antibodies against ciprofloxacin with broad specificity to fluoroquinolones were prepared. The newly developed magnetic particle-based competitive enzyme immunoassay was performed in a homogeneous sample, and ciprofloxacin was quantitatively detected in the range of 0.3-24.3 ng mL-1. The IC50 and LOD values of the method were 2.27 ng mL-1 and 0.25 ng mL-1. In chicken muscle, the recoveries of spiked ciprofloxacin at 8, 20, and 40 ng mL-1 were all higher than 79%. Additionally, the performance of the developed magnetic particle-based immunoassay exhibited an excellent correlation with commercial ELISA kits (r = 0.997). The anti-ciprofloxacin monoclonal antibodies provided high cross-reactivity with eight fluoroquinolones analogues: enrofloxacin (110.1%), sarafloxacin (99.7%), difloxacin (90.2%), danofloxacin (89.8%), norfloxacin (110.3%), lomefloxacin (65.2%), ofloxacin (75.1%), and flumequine (45.0%). This protocol provides an alternative immunoassay for ciprofloxacin with the advantages of simple separation, a homogeneous reaction, rapid detection (within 30 min), and stable results. Furthermore, it may be employed for the rapid general determination of fluoroquinolones in animal products. © 2014 Taylor & Francis Group, LLC.


Zhang L.,Nankai University | Song Z.,Nankai University | Dong Y.,Nankai University | Wang Y.,Nankai University | And 8 more authors.
Journal of Supercritical Fluids | Year: 2016

Chiral separation of seven commonly used 1,4-dihydropyridines (1,4-DHP) was achieved by supercritical fluid chromatography (SFC) on a immobilised polysaccharide chiral selectors coated with cellulose-tris(3,5-dichlorophenylcarbamate) (Chiralpak IC). In this method, isopropanol was used as a modifier and a maximum resolution of 13.38 was resulted. Nimodipine content of actual samples was determined through two-phase hollow fibre-based liquid-phase microextraction (2p-HF-LPME). Under optimal conditions, the limits of detection of the two nimodipine enantiomers were 0.3 and 0.5 μg cm-3. Recoveries of 80.0-99.8% were achieved. The developed SFC technique coupled with 2p-HF-LPME is a rapid, effective and environment-friendly method for separating and quantifying 1,4-DHP enantiomers. © 2015 Elsevier B.V. All rights reserved.

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