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

The analytical performances of a lateral flow immunoassay (AFLA-V AQUA(TM), 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 ug 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 ug kg-1 or 4 mg kg-1 as the screening target concentration were 1.24 and 2.18 ug 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.