Immunochromatographic assay for the rapid and sensitive detection of etoxazole in orange and grape samples
Jie Liu, Xinxin Xu, Aihong Wu, Shanshan Song, Liguang Xu, Chuanlai Xu, Hua Kuang, Liqiang Liu
Abstract
Etoxazole, a novel organofluorine pesticide, has been widely used against various mites in fruits and vegetables. In this study, we designed an etoxazole-hapten and produced a highly sensitive monoclonal antibody (mAb) against etoxazole with a half-maximal inhibitory concentration of 4.04 ng/mL. Based on the mAb, we developed an immunochromatographic assay (ICA) for the detection of etoxazole in orange and grape samples. In the qualitative detection, the visible limit of detection (vLOD) and cut-off value were 10 and 100 ng/g (fresh weight), respectively. In the quantitative detection, the LOD value was 2.03 ng/g (fresh weight) in orange and 2.52 ng/g (fresh weight) in grape samples. The recovery rates ranged from 94.7 ± 4.0% to 103.3 ± 3.8%, with CVs of 3.7–4.2% and 96.4 ± 3.4% to 106.1 ± 5.5%, with CVs of 3.5–5.2% for etoxazole in grape and orange samples, respectively. The ICA results were similar to those of LC-MS/MS. Therefore, our developed ICA is a rapid, sensitive, and simple tool for screening etoxazole residues in fruits and vegetables.