Validation of a lateral flow immunoassay for the rapid determination of aflatoxins in maize bysolvent free extraction

Analytical performances of a commercial lateral flow immunoassay for the determination of aflatoxins in maize after water-based extraction, were evaluated according to Commission Regulation (EU) No 519/2014. The validation study was performed at AFB1 levels encompassing EU maximum permitted levels (up to 8 µg/kg), and provided information on method precision, cut off values, false suspect and false negative rate. The total precision expressed as relative standard deviation, varied from 14 to 29% for contaminated samples. Cut off values calculated considering 2 µg/kg or 4 µg/kg as screening target concentration were 1.24 and 2.18 µg/kg respectively, whereas false suspect rate for blanks was 42% and 8 % respectively. The false negative rate for samples containing the analyte at higher concentrations resulted to be lower than 1%, thus complying with the regulation criterion of maximum 5%. Analysis of naturally contaminated maize samples performed by the lateral flow immunoassay and the AOAC official method revealed a good correlation (parameters of the linear regression: r = 0.97, slope = 0.96) between the obtained results. Sufficient agreement between reference values and test results was also obtained in the analysis of reference materials. The overall results of validation experiments gave a quite informative picture of kit performances for its use for different purposes, such as robustness among different maize varieties, acceptable performances for compliance testing at EU maximum permitted levels, sufficient accuracy and precision in discriminating samples contaminated at different AFB1 levels set in very narrow working range as required by EU regulatory limits. This especially applies to the scenario, when using 4 µg/kg as screening target concentration. Finally, a QC protocol based on guidelines suggested in EU regulation was designed to verify kit performances over the time and in new production lots.JRC.F.5-Food and Feed Complianc