Evaluation of enzyme-linked immunoassays for the determination of chloroacetanilides in water and soils

Reliable and sensitive indirect ELISAs for the quantitative determination of metolachlor, alachlor, and acetochlor were developed. Each herbicide was conjugated to a carrier protein via thioether linkage, and the product was used either as an immunogen or to prepare coating conjugates. The suitability of using the same chemical strategy to raise polyclonal antibodies against chloroacetanilides structurally related compounds and their metabolites is discussed. Under best conditions, detection limits of 0.06, 0.3, and 0.4 mug/L for metolachlor, alachlor, and acetochlor were reached, respectively. The optimized ELISAs were also highly specific, showing little or no cross-reactivity to other similar compounds. Immunoassays were used as a tool to determine critical chloroacetanilide herbicides in water and soil samples without purification steps. The excellent recoveries obtained (mean value ranging between 90% and 98%) confirm the potential of this approach to control these herbicides in the environment being applied as a "screening" method either for field monitoring or laboratory.