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

Abstract

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 optimised 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 limit of quantification (LOQ) and detection (LOD) 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 test its efficacy and gain some preliminary data about fumonisin contamination in dog food available in the Italian market. FB1 and FB2 were detected in all samples analysed and, in particular, 63.41% and 56.10% of the samples showed concentrations above the LOQ of FB1 and FB2, respectively. The levels of contamination quantified ranged between LOQ 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 fumonisin contamination of 5.19 µg/g and one complementary food a contamination of 8.80 µg/g.