APPLICATION OF IMMUNOASSAYS TO STUDIES OF THE ENVIRONMENTAL FATE OF ENDOSULFAN

A comprehensive validation of three endosulfan immunoassays (two micro well assays and a tube assay) using field samples was conducted as par t of a study on the environmental fate of endosulfan applied to Austra lian cotton fields. The validation included an initial examination of the relationship between tube and microwell immunoassays and then corr elations between immunoassay data and gas-liquid chromatography (GLC) analyses for several thousand water (in a format with a detection limi t of 0.2 mu g L-1) and soil samples and hundreds of aerial drift sampl es. In all cases, the immunoassay data proved to be closely correlated with GLC analyses, indicating that these immunoassays provide a relia ble quantification of endosulfan. Validation of immunoassay methods ag ainst GLC by providing reliable correlations was an important result, but in this study immunoassay also was useful in the research program for improving protocols for sampling and analysis by GLC. This was pos sible because of the demonstrated advantages of immunoassay for greate r speed and higher sample throughput with less complicated sample prep aration, which allows many more samples to be analyzed and a more comp rehensive study of field processes such as rain simulation. The abilit y of immunoassay to provide a summation of the three toxic forms of en dosulfan (alpha, beta, and sulfate) was exploited. It is concluded tha t this immunoassay for endosulfan is quantitative using soil, water, a nd aerial drift samples and that it would allow the possibility of dec ision making at field sites, improving environmental management of end osulfan residues.