Development of a monoclonal antibody-based enzyme-linked immunosorbent assay for the analysis of the new fungicide 2-allylphenol in strawberry fruits

2-Allylphenol (2-AP) is a recently registered fungicide in China to control fungal diseases on tomato, strawberry and apple. Four haptens were designed to produce 2-AP specific antibodies in the present work. A sensitive and specific indirect competitive enzyme-linked immunosorbent assay (icELISA) was developed with mAb225# for the analysis of 2-AP after it is derivatized with 4-aminobenzoic acid. The icELISA showed a concentration of 4-carboxy-3′-allyl-4′-hydroxyazobenzene (CAH) as 2-AP equivalent producing 50% inhibition (IC50) and a calibration range of 0.29 and 0.09–1.09 ng/mL, respectively. No competitive inhibition was observed up to 10,000 ng/mL of 4-aminobenzoic acid, 2(2-hydroxypropyl) phenol, salicylic acid, and 4-butanoylphenol. Average recoveries of 2-AP from strawberry samples spiked at concentrations from 156 to 5000 ng/g ranged from 83% to 95%. Comparable concentrations (R2, 0.996) of 2-AP in strawberry samples determined with the icELISA and high performance liquid chromatography suggest that the icELISA is suitable for analyses of 2-AP residues in strawberry.