Determination of 2,4-dichlorophenoxyacetic acid in cereals by fluorescence polarization immunoassay

A fluorescence polarization immunoassay (FPIA) procedure is developed for the determination of 2,4-dichlorophenoxyacetic acid in cereal grains using a Sentry-200 portable device. We synthesized tracers, that is, antigens labeled with fluorescein derivatives, based on two fluorescent compounds and two chlorophenoxyacids. The tracer synthesized from 2,4-dichlorophenoxyacetic acid and 4-aminomethylfluorescein is found to be optimal for the FPIA of 2,4-dichlorophenoxyacetic acid. The limit of detection for 2,4-dichlorophenoxyacetic acid in flour was 40 ng/g; the analytical range is from 80 to 1000 ng/g. The percentage of recovery was 85 ± 7% at the relative standard deviation (RSD) 2–10%.