Formation of protein-bound residues of the fungicide chlorothalonil in tomatoes (Lycopersicon esculentum Mill.)

Abstract

Adding the fungicide chlorothalonil to homogenized tomatoes leads to formation of bound residues in a pH dependent reaction. Recoveries of the fungicide ranged from 84% in pulps with natural pH (4.2) to 7% in pulps with alkaline pH (10.0). Incubation experiments with different model constituents, e.g. carbohydrates, organic acids, and proteins, showed that only the latter were responsible for the very low recoveries of the fungicide. Accordingly, in spiked protein solutions and in spiked tomato pulp, protein-bound residues of chlorothalonil were detected by a dot-blot immunoassay as a structure-specific method.