Determination of Diniconazole in Agricultural Samples by Sol-Gel Immunoaffinity Extraction Procedure Coupled with HPLC and ELISA

BACKGROUND In the European Union (EU), the use of diniconazole-M is no longer authorized. However, residues of diniconazole-M occur in various plant commodities. METHODOLOGY/PRINCIPAL FINDINGS A selective and simple analytical method for the trace level determination of diniconazole in soil, fruit, vegetables and water samples was developed based on immunoaffinity extraction followed by Enzyme-linked immunosorbent assay (ELISA) and the high-performance liquid chromatography (HPLC) analysis. The ELISA was based on monoclonal antibodies highly specific to diniconazole and was a fast, cost-effective, and selective screening method for the detection of diniconazole. The results of the ELISA correlated well with gas chromatography (GC) results, with the correlation coefficient of 0.9879 (n = 19). A simple gel permeation chromato- graphy clean-up method was developed to purify extracts from matrices containing high amounts of fat and natural pigments, without the need for a large dilution of the sample. The immunoaffinity column (IAC) capacity was 0.180 mg g(-1). The columns could be re-used approximately 20 times with no significant alteration in capacity. The recoveries from complex samples were in the range of 89.2% to 96.1% with a relative standard deviation (RSD) of 0.770%-6.11% by ELISA. The results were in good agreement with those obtained by HPLC method. CONCLUSION/SIGNIFICANCE The IAC extraction procedure coupled with HPLC and ELISA analysis could be also used as alternative effective analytical methods for the determination of diniconazole concentrations in complex samples.