Analysis of the Fungicide Boscalid in Horticultural Crops Using an Enzyme-Linked Immunosorbent Assay and an Immunosensor Based on Surface Plasmon Resonance

A direct competitive enzyme-linked immunosorbent assay (dc-ELISA) and an immunosensor based on surface plasmon resonance (SPR-sensor) were developed for fungicide boscalid determination in horticultural crops. To produce antiboscalid monoclonal antibodies (MoAb BSC7 and MoAb BSC72) for these assays, a hapten of boscalid was synthesized and conjugated to keyhole limpet hemocyanin for Balb/c mouse immunization. The working range of the dc-ELISA was 0.8–16 ng/mL with MoAb BSC7 and 2.5–120 ng/mL with MoAb BSC72, and that of the SPR-sensor was 17–80 ng/mL with MoAb BSC7. The dc-ELISA and SPR-sensor were compared for their sensitivity in determining boscalid residues at the maximum residue limit of 1–40 mg/kg for horticultural crops in Japan. Recovery of the spiked boscalid was 85–109% by the SPR-sensor and 100–124% by the dc-ELISA. On real tomato samples, the results obtained by both of these immunoassays correlated well with the results obtained by high-performance liquid chromatography.