Fluorescence polarization immunoassay for rapid screening of the pesticides thiabendazole and tetraconazole in wheat

Fluorescence polarization immunoassays (FPIAs) for thiabendazole and tetraconazole were first developed. Tracers for FPIAs of thiabendazole and tetraconazole were synthesized and the tracers’ structures were confirmed by HPLC-MS/MS. The 4-aminomethylfluorescein-labeled tracers allowed achieving the best assay sensitivity and minimum reagent consumption in comparison with aminofluorescein-labeled and alkyldiaminefluoresceinthiocarbamyl-labeled tracers. Measurements of fluorescence polarization were performed using a portable device. The developed FPIA methods were applied for the analysis of wheat. Fast and simple sample preparation technique earlier developed by authors for pesticides was adapted for thiabendazole and tetraconazole. The limits of detection of thiabendazole and tetraconazole in wheat were 20 and 200 μg/kg, and the lower limits of quantification were 40 and 600 μg/kg, respectively. The recovery test was performed by two methods—FPIA and HPLC-MS/MS. The results obtained by FPIA correlated well with those obtained by HPLC-MS/MS (r2 = 0.9985 for thiabendazole, r2 = 0.9952 for tetraconazole). Average recoveries of thiabendazole and tetraconazole were 74 ± 4% and 72 ± 3% by FPIA, and average recoveries of thiabendazole and tetraconazole were 86 ± 2% and 74 ± 1% by HPLC-MS/MS (n = 15).