Development of fluorescence polarisation immunoassay for carbofuran in food and environmental water samples

A simple and rapid method for determination of carbofuran was developed using the fluorescence polarisation immunoassay (FPIA). Three tracers with different lengths of bridge (0-, 2- and 6-carbon bridge) between the hapten molecule 4-[[(2,3-dihydro-2,2-dimethyl-7-benzofuranyloxy)carbonyl]-amino]-butanoic acid (BFNB) and 5-aminofluorescein (AF), fluoresceinthiocarbamyl ethylenediamine (EDF), fluoresceinthiocarbamyl hexylenediamine (HDF), were synthesised and their binding response with anti-carbofuran-specific antibody were evaluated. The physicochemical parameters were optimised for the FPIA. The AF-labelled BFNB conjugate (BFNB-AF) was found to be the optimal tracer for FPIA of carbofuran. The detection limit of carbofuran, IC₅₀ value and the working range were 2.3, 48.8 and 7.4−202.2 µg/L, respectively; and the reaction time was only 10 min. The average recovery from spiked water and vegetable samples was 86.9−95.4% and the mean coefficient of variation was 6.2% for inter-assay and 8.7% for intra-assay, which showed good reproducibility for FPIA. Thus, the developed FPIA method exhibited the potential for the rapid and accurate determination of carbofuran in agricultural and environmental samples.