1Fermentation Technology and Bioengineering Department, Central Food Technological Research Institute (CSIR), Mysore, Karnataka, India.
A simple competitive immunoassay was developed for the measurement of isoprothiolane in rice, soil, and water samples. It employed the avian antibodies (IgY) that recognized isoprothiolane as a capture reagent and isoprothiolane-alkaline phosphatase conjugate as an enzyme label. The assay depended on the competitive binding between the anti-isoprothiolane antibody and isoprothiolane derived from rice, soil, and water samples for binding sites with immobilized isoprothiolane-ovalbumin (OVA) conjugate. The concentration of isoprothiolane in the rice, soil, and water samples was quantified by the ability of the pesticide present in the samples to inhibit the binding of the enzyme conjugate to the antibody and subsequently the color formation in the assay. The assay was specific to isoprothiolane with a limit of detection of 2 ng/mL. Mean analytical recovery of isoprothiolane in different rice matrices was 87.20%-98.02%, for soil samples recovery was 74.24%-111.20%, and water samples recovery was 35.2%-95.73%. The precision of the assay was satisfactory. The assay compared favorably with gas chromatography (GC) in its ability to accurately measure isoprothiolane in the different rice, soil, and water samples.