High-affinity Antibodies from a Full Penthiopyrad-mimicking Hapten and Heterologous Immunoassay Development for Fruit Juice Analysis

New-generation succinate dehydrogenase inhibitors with increased antifungal performance have been developed during the last years. Particularly, penthiopyrad has been recently introduced in the agrochemical market as a complementary fungicide for combined treatments with other active principles displaying a different mode of action. In the present study, rapid and high-throughput analytical methods for penthiopyrad residue determination in foodstuffs were developed. A novel functionalized hapten that completely mimics the molecule of penthiopyrad was designed for high-affinity and specific antibody generation. Moreover, heterologous haptens were synthesized, and the influence of their respective molecular modifications over antibody binding was evaluated by competitive enzyme-linked immunosorbent assay. Two immunoassays were optimized using alternative assay formats, affording limits of detection for penthiopyrad in buffer around 0.07 ng/mL in both cases. Performance, in terms of accuracy and precision, of the developed immunochemical methods was studied using apple juice and red and white grape juices. The obtained results showed that penthiopyrad could be determined in those food samples in compliance with European maximum residue limits.