Fumonisin B1 and B2 in dry dog food: preliminary study on commercial samples

A reliable liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the identification and quantification of fumonisin B1 (FB1) and fumonisin B2 (FB2) in complete and complementary formulations of dry dog foods has been optimized and validated. The sample preparation consists of an extraction step followed by immunoaffinity clean-up. Method performance characteristics were evaluated spiking blank samples on multiple levels in four replicates. The method showed appropriate performance characteristic: good values of recovery (> 95.9 %) and precision (RSD < 6.8 %), as well as satisfying linearity of calibration curves (r2 ≥ 0.99). The limits of quantification (LOQs) and detection (LODs) were 0.100 μg/g and 0.005 μg/g, respectively, both in complete and complementary dry dog foods and both for FB1 and FB2. This method was applied to 41 commercial samples in order to tests its efficacy and gain some preliminary data about fumonisins contamination in dog foods available in the Italian market. Fumonisin FB1 and FB2 were detected in all samples analyzed and in particular 63.41 % and 56.10 % of the samples showed concentrations above the LOQs of FB1 and FB2, respectively. The levels of contamination quantified ranged between LOQs and 5.87 μg/g and 2.93 μg/g for FB1 and FB2, respectively. Among the complete dry dog foods, standard formulations generally showed an average fumonisins contamination higher than premium formulations. The guidance value of 5 μg/g set by Commission Recommendation 2006/576/EC for the sum of FB1 and FB2 was exceeded in two samples: one standard complete dry dog food showed a total fumonisins contamination of 5.19 μg/g and one complementary food a contamination of 8.80 μg/g.