Total aflatoxins in corn: analytical performance of two elisa kit

A careful and accurate control of corn for the presence of Aflatoxins (AFs) is crucial since they represent a risk both for agriculture and for human and animal health, in particular AF B1 is recognized as the most potent hepatocarcinogenic of natural origin for human (1). For these reasons accurate, sensitive, reproducible and rapid methods are required to guarantee food safety. The aim of this work was to evaluate two commercial ELISA kits (A and B) in terms of reliability and accuracy to establish the level of contamination in corn samples by AFs. Both kits used had the same analytical procedure (direct and competitive) and also the same range of determination (1-20ppb). To evaluate the reliability in terms of analytical response, the results obtained from kit analysis, were compared with those obtained by liquid chromatographic analysis (HPLC) of corn samples fortified with AFs in the concentration range of 2.16 to 18.49 ppb (4 points, 4 replicates each). The average of the values of kit B deviated from the statistical point of view, significantly, from values obtained after HPLC analysis, while the curve of the results obtained from analysis by kit A, was comparable to that obtained with chromatography. The recovery and repeatability of ELISA kits were evaluated taking into account the performance criteria for methods for determining AFs according to European Regulation 401/2006/EC. Kit A showed medium recovery always greater than kit B, characterized by recovery rates next to the minimum performance values required. Kit B therefore underestimates the AFs concentration in corn samples, especially for the lower levels of contamination, confirming his lowest reliability and accuracy. Regarding repeatability (RDS%), an index of accuracy, was acceptable at all concentration levels for both kits, respecting the criteria imposed by European Regulation 401/2006/EC (2). Finally, we evaluated the analytical performance over time of ELISA kits in three different sessions of work, after 10 days apart (T0, T10, T20). Both kits maintained unchanged analytical performance up to 20 days after the opening, if properly stored.