Highly sensitive monoclonal antibody-based immunoassays for the analysis of fluopyram in food samples

Monoclonal antibody-based techniques have become a useful analytical technology in the agro-food sector. Nowadays, residues of the recently registered fungicide fluopyram are increasingly being found in quality control programs. In the present study, novel chemical derivatives of this pesticide were prepared and specific and high-affinity monoclonal antibodies to fluopyram were raised for the first time. Moreover, immunoassays to fluopyram were developed in two alternative enzyme-linked immunosorbent assay formats, using homologous and heterologous assay conjugates, with limits of detection below 0.05 µg L^-1. The optimized immunoassays were applied to the analysis of fluopyram in fortified plums and grapes of four different varieties as well as in in-house prepared musts and wines. Recoveries were between 76.3% and 109.6% and coefficients of variation were below 20%. Quantification limits were well below the maximum residue limits. Immunoassay performance was statistically validated with a reference chromatographic technique using samples from fluopyram-treated plum and grape cultivars.