Development of monoclonal antibody-based competitive immunoassays for the detection of picoxystrobin in cereal and oilseed flours

Picoxystrobin is a new generation fungicide primarily developed to be used in cereal crops. In the present study a novel collection of specific monoclonal antibodies has been produced using different immunizing haptens based on a carboxy-functionalized identical spacer arm attached to alternative positions of the target pesticide molecule. Two competitive enzyme-linked immunosorbent assays have been developed employing hapten heterology, one using the antibody-coated direct format and the other in the conjugate-coated indirect format. Both immunoassays have been characterized in terms of selectivity, solvent tolerance, and buffer conditions, affording similar limits of detection at or below 0.1 μg/L. Finally, the optimized assays were applied to the analysis of picoxystrobin in wheat, corn, oat, barley, and soybean flours. Average recovery values from spiked samples were between 84 and 115%.