Development of a quantitative lateral flow immunoassay for the detection of aflatoxins in maize.

An immunoassay-based lateral flow device for the quantitative determination of four major aflatoxins in maize has been developed. The one-step assay has performance comparably with that of other screening methods, as confirmed by the intra- and the inter-day precision of the data (RSD 10-22%), and can be completed in 10 min. Quantification was obtained by acquiring images of the strip and correlating intensities of the coloured lines with analyte concentration by means of a stored calibration curve carried out by diluting aflatoxins in the extract from a blank maize sample. Limit of detection (1 µg kg⁻¹) and dynamic range (2-40 µg kg⁻¹) allows the direct assessment of aflatoxin contamination in maize at all levels of regulatory relevance. All reagents are immobilized on the lateral flow device. In addition, very simple sample preparation, using an aqueous buffered solution, has been demonstrated to allow the quantitative extraction of aflatoxins. Twenty-five maize samples were extracted with the aqueous medium and analyzed by the developed assay. A good correlation was observed (y = 0.97x + 0.07, r²= 0.980) when data was compared with that obtained through an official method. The developed method is reliable, rapid and allows for application outside the laboratory as a point-of-use test for screening purposes.