Development of an enzyme-linked immunosorbent assay for isoproturon in water

A competitive enzyme-linked immunosorbent assay (ELISA) suitable for the determination of the urea herbicide isoproturon [3-(4-isopropylphenyl)-1,1-dimethyl urea] in water has been developed. A derivative of isoproturon [3-(4-isopropylphenyl)-1-carboxypropyl-1-methyl urea] has been synthesized and linked to thyroglobulin using the N-hydrosuccinimide reaction. The immunogen was used to immunize two sheep, which both responded by producing specific antibodies to isoproturon with little cross-reactivity to various structurally related and unrelated pesticides. The enzyme label was prepared by coupling the hapten to horseradish peroxidase using the above reaction. The coated-antibody competitive ELISA, which has a sensitivity of 0.03 microgram l-1, permits the direct determination of isoproturon in various water matrices and can facilitate the monitoring of water quality in drinking-water supplies.