Optimization of a Direct Competitive Enzyme-Linked Immunoassay for Carbofuran and Application to Water Samples

Abstract

A direct competitive enzyme-linked immunosorbent assay (ELISA) for carbofuran was developed, which was based on the anti-BFNB IgG monoclonal antibody (McAb) and a homologous enzyme tracer (BFNB-HRP). The influence of several physicochemical factors (salt, pH, detergent, and solvent) on the immunoassay was studied. For the standard curve, an I₅₀ of 2.98 µg/l and a limit of detection (I₁₀) of 0.27 µg/l was obtained in a high salt concentration buffer (0.08 M PBS, pH 7.0) with 0.03% BSA. A common challenge for immunoassay, time-dependent drift, was effectively circumvented in our study. The optimized ELISA has been used to quantify carbofuran in water samples spiked at different amounts. The excellent recoveries (71% to 130%) achieved confirmed the potential of the immunoassay for monitoring of carbofuran in waters without purification steps.

Keywords:

• Carbofuran
• ELISA
• Monoclonal antibody
• Time-dependent drift

This work was supported by the National Natural Science Foundation of China (30370944) and Zhejiang Key Technologies R & D Program (2006C12102). We are very grateful to Zhejiang Health Creation Biotech Co. Ltd. for financing support.

Notes

^a SD (standard deviation n = 4)

^b CV (coefficient of variation): data obtained from four determinations performed in the same ELISA plate.