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

Abstract

The analytical performances of a lateral flow immunoassay (AFLA-V AQUA™, Vicam a Waters Business) for the determination of aflatoxins in maize were evaluated according to Commission Regulation (EU) No. 519/2014. This case study showed how a critical evaluation of validation results can provide a quite informative picture of kit performances for its use for different purposes. The validation study, performed at aflatoxin B₁ levels encompassing EU maximum permitted levels (up to 8 μg kg⁻¹), provided information on the method precision profile, cut off values, and false suspect and false negative rates. The total precision expressed as relative standard deviation varied from 14 to 29% for contaminated samples. Cut off values calculated considering 2 μg kg⁻¹ or 4 μg kg⁻¹ as the screening target concentration were 1.24 and 2.18 μg kg⁻¹, respectively, whereas the resultant false suspect rate for blanks was 42% and 8%, respectively. The false negative rate for samples containing the analyte at higher concentrations was found to be lower than 1%. 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. A satisfactory agreement between reference values and test results was also obtained in the analysis of reference materials. Finally, a QC protocol based on guidelines suggested in the EU regulation was designed to verify kit performances over time and in new production lots.