Development of an indirect enzyme immunoassay for the determination of thiabendazole in white and red wines

Abstract

A competitive indirect enzyme immunoassay for the determination of fungicide thiabendazole in white and red wine samples was developed. The assay had a detection limit of 0.005 ng mL−1, a dynamic range from 0.01 to 2 ng mL−1, and was precise with intra- and inter-assay coefficient of variation values less than 5% and 8%, respectively. Concerning the sample preparation procedure, it was found that filtration of the wine samples through a 0.45 μm pore size polytetrafluoroethylene (PTFE) filter followed by 30 times dilution with the assay buffer eliminated completely matrix interferences for both white and red wines derived from different grape varieties. This was demonstrated by the accurate determination of thiabendazole amounts in spiked wine samples (% recovery 90.6–108). In addition, the results obtained for certain spiked wine samples were in good agreement with those received by an LC-MS/MS method for determination of thiabendazole in wines. Taking into account the dilution factor, the thiabendazole concentrations that could be determined in wines ranged from 0.3 to 60 ng mL−1. The maximum residue limit (MRL) of thiabendazole in wine grapes is 50 μg kg−1. Thus, the proposed enzyme immunoassay can be applied for the fast and parallel analysis of a high number of white and red wine samples with minimal sample pre-treatment.