Development of fluorescence polarization immunoassays for parallel detection of pesticides carbaryl and triazophos in wheat grains

Fluorescence polarization immunoassays (FPIA) were developed for the determination of pesticides triazophos and carbaryl in wheat grains using the portable FPIA device Sentry 200 (Ellie). FPIA of carbaryl was developed first. Tracers for FPIA were synthesized and their structures were confirmed via mass spectrometry. The influence of tracer cross-linking bridge length on the assay sensitivity was estimated. The use of tracers labeled with ethylenediamine fluorescein thiocarbamyl (EDF) resulted in the best assay sensitivity with minimal reagent consumption. A rapid and easily performed sample preparation technique that allowed the parallel determination of both analytes in aliquots of the same sample was developed. The detection limits for triazophos and carbaryl were 40 and 20 mg kg(-1), respectively, and the measurement ranges were 40-200 and 60-650 mg kg(-1), respectively. A recovery test was performed using FPIA and high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), and the results obtained showed good correlation (r(2) = 0.9843 for triazophos, r(2) = 0.9916 for carbaryl).