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  g 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 from 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 (R² > 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.