CLOMAZONE MEASUREMENT BY ENZYME-LINKED-IMMUNOSORBENT-ASSAY

An indirect, competitive, enzyme-linked immunosorbent assay (ELISA) was developed for the measurement, in soil, of clomazone [FMC 57020, 2-[(2-chlorophenyl)methyl]-4,4-dimethyl-3-isoxazolidinone], the active ingredient of Command herbicide. The p-aminophenyl analogue of clomazone was used to prepare a bovine serum albumin conjugate for immunization of rabbits. With soil, the sensitivity limit is about 10 ppb and the detection limit is about 5 ppb. The detection range in soil extends from 10 ppb to 1.25 ppm. The method described here uses simple aqueous extraction of soil and permits a throughput of several hundred samples per week when a computer-controlled plate reader is used. The correlation coefficient of this method compared to a GLC method by linear regression is 0.98. A correlation between the amount of clomazone herbicide residue detected in soil by ELISA and the level of plant injury it caused in bioassay is demonstrated. Several analogues of clomazone, substituted in the para position of the phenyl ring, showed cross-reactivity with the antibody. None of the cross-reacting analogues are metabolites of clomazone. In general, substitutions on the isoxazolidinone ring resulted in large decreases in cross-reactivity.