Cephalexin Residue Detection in Milk and Beef by ELISA and Colloidal Gold Based One-Step Strip Assay
Cephalexin Residue Detection in Milk and Beef by ELISA and Colloidal Gold Based One-Step Strip Assay
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DOI：
10.1021/jf900433d
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发表时间：
2009-06-10
影响因子：
6.1
通讯作者：
Han, Bo
中科院分区：
文献类型：
--
作者：
Chen, Liben;Wang, Zhengfang;Han, Bo
建立了牛奶和牛肉中头孢氨苄（CEX）残留的快速酶联免疫吸附试验（ELISA）和胶体金一步法检测方法。以头孢氨苄-牛血清白蛋白（CEX-BSA）偶联物为免疫原，制备了抗CEX的单克隆抗体（mAb），在研究的浓度范围内，该抗体与所用化学品无交叉反应。快速ELISA的检测限为0.39 μ g/kg（PBS）和19.5 μ g/kg（牛肉和牛奶），远低于欧盟规定的牛奶和肌肉中的最大残留限量（MRL）（分别为100 μ g/kg和200 μ g/kg）。加标样品的平均回收率为82.8-124%，变异系数为4.88- 25%，与加标浓度吻合良好。使用四种不同终浓度CEX（n = 7）的加标样品测定准确度和重现性，所述终浓度为1、2、5和10 μ g/kg。平均批内变异为6.67%，批间变异为10.66%。相比之下，CEX试纸条检测的目视检测限为0.5 μ g/kg，可在3-10 min内进行评估。然而，阳性样品应通过更灵敏、更准确的竞争性间接ELISA方法进一步定量。总之，所描述的试纸条测试是快速、简单和具有成本效益的，并且灵敏度和特异性足以用于可靠和准确的现场筛查。
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 mu g/kg in PBS and 19.5 mu g/kg in beef and milk, which was quite lower than the European Union Maximum Residue Limit (MRL) of 100 mu g/kg in milk and 200 mu g/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 mu g/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 mu g/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.