Development of an enzyme-linked immunosorbent assay for diniconazole in agricultural samples

Diniconazole hapten was synthesized and conjugated to bovine serum albumin (BSA) by the carbodiimide method to produce an immunogen and to ovalbumin (OVA) by mixed anhydride method to produce a coating antigen. Polyclonal antibody against diniconazole was generated by immunizing New Zealand rabbits with the immunogen. Under optimised conditions (20% methanol, 0.4 mol/L Na⁺, pH 7.5), an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) was developed for detecting diniconazole. The 50% inhibitory concentration (IC₅₀) was 0.071 ± 0.013 mg/L and the limit of detection (LOD) was 1.28 ± 0.80 μg/L. Triazole fungicide analogues of diniconazole were tested and did not obviously cross-react, except for uniconazole (2.25%). The recoveries obtained after addition of standard diniconazole to agricultural samples, including water, soil, pear, grape, tomato and wheat flour, ranged from 70% to 120%. The ic-ELISA developed could successfully be applied to analysis of diniconazole residues in agriculture samples.