Development of an Immunosensor for Determination of the Fungicide Chlorothalonil in Vegetables, Using Surface Plasmon Resonance.

Yuki Hirakawa, Tomomi Yamasaki, Eiki Watanabe, Fumiko Okazaki, Yukie Murakami-Yamaguchi, Masayuki Oda, Seiji Iwasa, Hiroshi Narita, Shiro Miyake

Index: J. Agric. Food Chem. 63 , 6325-30, (2015)

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Abstract

An immunosensor based on surface plasmon resonance (SPR-sensor) was developed to analyze chlorothalonil residues and maximum residue limits (MRLs; 0.5-50 mg/kg) in vegetables in Japan. Conjugates of N-(pentachlorophenoxyacetyl)glycine and bovine serum albumin were covalently coated on the sensor chip. The SPR-sensor quantitatively determined chlorothalonil at concentrations ranging from 8.0 to 44 ng/mL, using TPN9A, a monoclonal antibody to chlorothalonil. The 50% inhibition concentration was 25 ng/mL. The reactivity was 10-fold lower than that of indirect competitive enzyme-linked immunosorbent assay (ic-ELISA). However, the SPR-sensor could determine chlorothalonil residues in vegetables at concentrations around the above MRLs. Chlorothalonil spiked in vegetables was recovered at 90-118% within 1 day and at 90-115% across 3 days, correlating with HPLC results. The sensor showed good performance for chlorothalonil residue analysis in vegetables with rapid determination, although the sensitivity and the cross-reactivity were less effective than with the ic-ELISA.