Validation of an LC-MS Method for Quantification of Mycotoxins and Characterization of Fungal Strains Occurring in Food and Feed

Mycotoxins are naturally occurring secondary metabolites produced by specific fungal strains. They can cause adverse effects, posing a serious health threat to both humans and livestock. Focusing on several mycotoxins, this study first aimed at optimizing and validating an ultra-high liquid chromatography-tandem mass spectrometry quantification method. This method was then applied to evaluate the production of the targeted mycotoxins in maize cultivated in the presence of Aspergillus spp., Fusarium spp., and Alternaria spp. The limits of detection of the analytical method for the different mycotoxins ranged between 0.5 and 200 μg kg−1, while the limits of quantification were between 1 and 400 μg kg−1. The linearities of the calibration curves were evaluated, with calculated R2 values above 0.99. The mean recoveries fell within the acceptable range of 74.0–106.0%, the repeatability was not higher than 14.4% RSD, and the highest intra-laboratory reproducibility was 16.2% RSD. The expanded measurement uncertainties ranged between 4.0% and 54.7%. Several fungal strains cultivated on maize grains were demonstrated to produce the targeted toxins, with production at µg kg−1 to mg kg−1 levels for aflatoxins and up to g kg−1 levels for fumonisins, zearalenone, and alternariol.