Development of an ELISA for the Detection of Fenazaquin Residues in Fruits

To develop an enzyme-linked immunosorbent assay (ELISA) for the detection of the residues of the acaricide fenazaquin, five haptens were synthesized and assessed. A competitive indirect format was used with polyclonal antibodies. Under an optimized condition using the selected rabbit C antiserum, an IC50 of 96.97 ng · ml −1 , the detection range of 14.9~631 ng · ml −1 , and the lowest detection limit of 8n g ·m l −1 were obtained. Some structurally related compounds of practical use showed low crossreactivities to the antibody. Highest cross-reactivity observed with hapten IV indicates that the antiserum C recognizes very well quinazoline ring, 4-tert-butylphenyl, and an adequate length of spacer arm. The length of spacer arm affected recognition of quinazoline ring and 4-tert-butylphenyl moieties. When applied to apple and pear, recoveries were within acceptable ranges of 93.18~104.77% (n = 4) and 79.40~111.95% (n = 4), respectively.