Determination of cutin-bound residues of chlorothalonil by immunoassay

An indirect competitive enzyme-linked immunosorbent assay (ELISA) was used to determine photochemically cutin-bound residues of chlorothalonil in enzy matically isolated tomato and apple fruit cuticles. The samples were spiked , irradiated, exhaustively extracted,and depolymerized with boron trifluori de complex resulting in a soluble depolymerisate. With this procedure, the ELISA could be calibrated with free target molecules for the quantification of originally bound chlorothalonil residues. In fruit cuticles that were i rradiated for 8 h by simulated sunlight, 0.030 and 0.068 mg/g photoinduced cutin-bound residues of wax-free cuticles (calculated as chlorothalonil) we re determined for tomatoes and apples, respectively. For the used antibody mAb chl. 4/11, cross-reactivities with derivatives of chlorothalonil simula ting different types of cuticle-bound residues are given and discussed.