Cephalexin Residue Detection in Milk and Beef by ELISA and Colloidal Gold Based One-Step Strip Assay

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• 作者：Liben Chen ; Zhengfang Wang ; Miro Ferreri ; Jingliang Su ; Bo Han
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2009
• 出版时间：June 10, 2009
• 年：2009
• 卷：57
• 期：11
• 页码：4674-4679
• 全文大小：802K
• 年卷期：v.57,no.11(June 10, 2009)
• ISSN：1520-5118

文摘

An evaluation of a rapid enzyme-linked immunosorbent assay (ELISA) and colloidal gold based one-step strip assay for cephalexin (CEX) residue detection in milk and beef is described. A monoclonal antibody (mAb) against CEX was produced using cephalexin−bovine serum albumin (CEX-BSA) conjugate as the immunogen, which exhibited no cross-reactivity with applied chemicals in the studied concentration range. The detection limit of rapid ELISA was calculated as 0.39 μg/kg in PBS and 19.5 μg/kg in beef and milk, which was quite lower than the European Union Maximum Residue Limit (MRL) of 100 μg/kg in milk and 200 μg/kg in muscle. Spiked samples were detected with a mean recovery of 82.8−124% and coefficient of variation of 4.88−25%, which indicated a good agreement with the spiked concentration. Accuracy and reproducibility were determined using spiked samples with four different final concentrations of 1, 2, 5, and 10 μg/kg of CEX (n = 7). Mean intra-assay variation of 6.67% and inter-assay variation of 10.66% were obtained. In contrast, the strip test for CEX had a visual detection limit of 0.5 μg/kg, which could be evaluated within 3−10 min. However, positive samples should be further quantified by more sensitive and accurate competitive indirect ELISA method. In conclusion, the described strip test is rapid, simple, and cost-effective as well as sensitive and specific enough for reliable and accurate on-site screening.