Fluorescence polarization immunoassay for the insecticide DDT and its metabolites

Two fluorescence polarization immunoassays (FPIA) for detection of the insecticide DDT (DDT-specific FPIA) and the sum of DDT isomers and metabolites (DDT class-specific FPIA) were developed. Various fluorescein-labeled tracers were synthesized and studied in order to achieve a high sensitivity using different monoclonal antibodies. For DDT-specific assay the sensitivity, estimated as limit of detection, was 12 ng/mL, with a linear working range between 20 and 1000 ng/mL. For DDT class-specific assay the sensitivity was 3 ng/mL, with a linear working range between 5 and 1000 ng/mL. Regarding specificity to other chlorinated pesticides, both immunoassays showed no cross-reaction (< 0.1%) with 2,4-D, endosulfan, diuron and hexachlorocyclohexanes. Both FPIAs were successfully applied to the analysis of DDT in spiked tap water samples. The FPIAs for DDT are simple, rapid and homogeneous (without separation and washing steps). Total time of analysis is less than 1 min per sample. The developed FPIAs could be used for rapid screening of water samples for contamination with DDT and its isomers and metabolites.