Development and Validation of an Immunoassay for the Determination of Tebuconazole Residues in Cereal Crops

A competitive ELISA for the quantitative detection of the triazole fungicide tebuconazole has been developed. For this purpose, polyclonal antibodies were raised in rabbits against two p-chloro substituted derivatives of tebuconazole conjugated to bovine serum albumin. A standard curve obtained with one of the antisera showed a linear detection range between 20 and 0.02 mug ml(-1) of tebuconazole in 20% methanol. Studies on the cross-reactivity of the antiserum to seven other commercially important triazole compounds showed little or no reaction. The validation of the ELISA was carried out using leaf samples fi-om. wheat plots, sampled 48 h after spraying with tebuconazole. The samples were subjected to two different extraction methods and tebuconazole residues analysed by GC-MS and ELISA. The results indicated a highly significant correlation (R-2 > 0.9821) between the two methods of analysis. The potential uses of the assay developed in relation to fungicide spray optimisation and reduction of fungicide use is discussed.