Evaluation of zearalenone in flours

Abstract

An analytical methodology based on extraction with acetonitrile:water (90:10), clean-up with immunoaffinity columns (IACs), and detection and quantification by liquid chromatography with fluorescence detection (LC-FD) was validated in order to evaluate zearalenone (ZEA) in different types of flours (wheat, maize, mixed cereals) used for human consumption with different purposes, originated from Coimbra (Portugal), Utrecht (The Netherlands) and Valencia (Spain). Linearity, in the working standards solutions, between 12.5 ng/mL and 200ng/mL, was good (r2=0.998). Linearity in the matrix-matched assay, prepared between 20 and 250μg/Kg, was r2=0.997. Matrix-effect was 92.5%. Recovery values ranged between 97.6 and 105.3%, and precision between 2 and 13.6%. The accuracy and precision results comply with the requirements established by the EC directive 401/2006. LOD and LOQ were 3.75 and 12.5μg/Kg, respectively. The application of the procedure to 50 samples from the three cities showed that 36% of the samples were contaminated. One sample with baby flour purpose exceeded the maximum limit established by EC legislation of 2007, and another one was close to the limit. A maize flour sample exceeded the ML established by EC with a concentration of 111.7μg/kg. Thus, two of the tested samples from Coimbra were contaminated above the established maximum limits for processed maize-based food for infants and maize intended for direct human consumption. The estimated daily intake (EDI) ranged between 0.013 and 0.14 g/kg b.w./day, which represents 52x102% and 560x102% of the TDI established by EFSA in 2011, 0.25 ng/kg b.w./day. Therefore, all the studied populations are at risk, being this risk higher for babies than for adults, both in Portuguese and Dutch population.