A sensitivity-improved enzyme-linked immunosorbent assay for fenvalerate: a new approach for hapten synthesis and application to tea samples

BACKGROUND: Fenvalerate has been widely used for the control of many common pests, but residues of this pesticide have been found in some agricultural crops. China is a large exporter of tea products; thus monitoring of pesticide residues in tea products has become increasingly important. In this study, a method of competitive direct enzyme‐linked immunosorbent assay (CD‐ELISA) for the rapid detection of fenvalerate in tea sample was developed. RESULTS: A polyclonal antibody against fenvalerate (FEN) was produced by the hapten with the characteristic moiety of fenvalerate. After acidification, the hapten was synthesized from 2‐(4‐chloro‐phenyl)‐3‐methyl‐butyric acid and aminocaproic acid methyl ester. The CD‐ELISA method developed has a high sensitivity of detection: 9 µg L^?1 for IC₅₀ and 0.5 µg L^?1 for IC₁₅. Fenvalerate was treated with 0.5 mmol L^?1 NaOH–methanol solution to improve its solubility by isomerization. In the tea sample, the detection limit of fenvalerate was 0.16 mg L^?1. A recovery rate of 76.67–91.43% was obtained from spiked tea. The reliability of the CD‐ELISA method is better in comparison with the gas chromatographic method (R² = 0.9968). CONCLUSION: In this study, a simple and efficient immunoassay method was developed. It is preferable for the rapid determination of fenvalerate residues in tea samples. Copyright © 2011 Society of Chemical Industry