Comparison of sulfonylurea herbicide residue detection in soil by bioassay, enzyme-linked immunosorbent assay and hplc

The ability of bioassay, enzyme-linked immunosorbent assay (ELISA) and high -performance liquid chromatography (hplc) methods to detect sulfonylurea he rbicides in soil was evaluated as part of a project studying the leaching a nd persistence of these herbicides in the alkaline soils of south-eastern A ustralia, Soil samples with known concentrations between 0.1 and 10 mu g a. i. kg(-1) chlorsulfuron, metsulfuron-methyl or triasulfuron were prepared b y an independent laboratory and supplied in coded bags to separate laborato ries for testing. The accuracy of the results was analysed, and the merits of each method are discussed. Bioassay was suitable for measuring biologica lly active residues from 0.1 to 1.0 mu g a.i. kg(-1). ELISA accurately meas ured residues in the range of 0.1-10 mu g a.i. kg(-1), making it the most w idely adaptable assay tested. It will be useful for measuring residues in s odic subsoils where bioassay plants grow poorly. There was good reproducibi lity between the bioassay and ELISA. The hplc technique used in this study was not as accurate as bioassay or ELISA at quantifying residues of 3.0-10 mu g a.i. kg(-1) and could not detect residues at or below 1.0 mu g a.i. kg (-1).