Abstract:The competition method was used to couple a monoclonal antibody against chlorothalonil with the rare earth europium florescent nanospheres to synthesize a fluorescent labeled immune probe. This probe was used with a highly sensitive and rapid lanthanide fluorescent immunochromatography card for the rapid quantification of chlorothalonil in vegetables and fruits through an immunoassay. In this study, a high sensitivity and specificity chlorothalonil antigen was selected, and the labelling conditions of fluorescent nanospheres and chlorothalonicin, coating concentration of flufenicomumab antigen on NC membrane, and proportion of diluted complex solution were optimized. The fluorescence test strip developed in this study was used in conjunction with a fluorescence detector and pre-treatment with low-dosage organic solvent. Herein, the optimum experimental conditions were the concentration of antigen was 0.05 mg/mL, and the concentration of antibody was 0.8 mg/mL, the pH of PBS working buffer was 7.2 (8% methanol). A standard curve was established, and the linear range of the method was 2~100 ng/mL with a detection limit of 0.2 mg/kg. The strip detection of chlorothalonil had strong specificity without any cross reaction observed in certain pesticides. The recovery rate of thiamethoxam was 85~98%, the intra-batch precision was 8%~12%, and the inter-batch precision was 11%~17%. There was no significant difference between the results of actual samples and the national standard method. The rapid time-resolved fluorescence assay developed in this study is fast, accurate, highly sensitive, and green and environmentally friendly, making it suitable for rapid and quantitative screening of chlorothalonil in food of plant origin.
