A validated multi-channel electrochemical immunoassay for rapid fumonisin B1 determination in cereal samples†
Fumonisin mycotoxins are natural contaminants of cereals mostly found in maize samples. Owing to their acute and chronic toxicity, very strict regulations have been imposed on the levels of fumonisin mycotoxins in cereal and cereal-based foods worldwide. We report a rapid direct competitive multi-channel electrochemical immunoassay for fumonisin B1 (FB1) determination in cereal and cereal-based foods. Monoclonal antibodies against FB1 were immobilized on the surface of modified magnetic beads (2.8 μm diameter), and the transduction was performed on an 8× screen-printed array allowing the multi-channel electrochemical detection of eight samples in parallel (amperometric detection, E = −0.35 V). The FB1 electrochemical immunoassay has a limit of detection of 0.58 ± 0.05 μg L−1 and EC50 = 4.34 ± 0.15 μg L−1, for FB1 concentration in the range of up to 54 μg L−1. The precision (within-day, between-days) was in the range of about 7–13% RSD. The optimized method (extraction and the electrochemical immunoassay determination) was successfully validated with maize certified reference materials at various levels of concentrations, and with an official AOAC liquid chromatography with fluorescence detection (HPLC-FLD) method (2001.04). We also compared our results with a commercial enzyme-linked immunosorbent analysis (ELISA) kit. Cross-reactivities with other mycotoxins (ochratoxins and deoxynivalenol) were less than 10%. The lifetime of immobilized antibodies was about 28 days. The reported FB1 multi-channel electrochemical immunoassay is a rapid and reliable alternative to HPLC methods.