Rapid and simple immunochemical screening combined with hand-shaking extraction for thiamethoxam residue in agricultural products

Authors


Correspondence to: Eiki Watanabe. National Institute for Agro-Environmental

Sciences, Tsukuba, Ibaraki 305–8604, Japan. E-mail: eikiw@affrc.go.jp

Abstract

Background

With the aim of expanding the applicability of a kit-based enzyme-linked immunosorbent assay (ELISA) for the neonicotinoid insecticide thiamethoxam, the ELISA was newly applied to three kinds of agricultural samples (green pepper, eggplant and spinach). To offer the ELISA as a screening analysis for thiamethoxam residues, a rapid and simple method of extraction by hand-shaking was used, and speed-up and simplification of the sample treatment before the ELISA analysis were examined. Finally, the validity of the ELISA combined with the proposed extraction method was verified against a reference high-performance liquid chromatography (HPLC) method using real-world agricultural samples.

Results

There were no marked matrix effects derived from green pepper and eggplant extracts. On the other hand, although the effect due to a pigment in spinach extract on the assay performance was significant, it was effectively avoided by increasing the dilution level of the spinach extract. For thiamethoxam-spiked samples, acceptable recoveries of 97.9–109.1% and coefficients of variation of 0.3–11.5% were obtained. Inspection of the validity of the ELISA by comparison with the reference HPLC method showed that the two analytical results were very similar, and a high correlation was found between them (r > 0.997).

Conclusion

The evaluated ELISA combined with hand-shaking extraction provided a rapid and simple screening analysis that was quantitative and reliable for the detection of thiamethoxam in complex agricultural products.© 2012 Society of Chemical Industry

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