Aflatoxin B1 and M1 in milk

• The mobile phase chosen consists acetic acid:acetonitrile:methanol (55:10:35).
• We obtained a separation factor of 2.3 for AFLAB1 and AFLAM1.
• The milk samples were contaminated by aflatoxins above the legislated limits.
• Aflatoxins tend to get attached to clot after acid precipitation of milk.

The aflatoxin M1 (AFLAM1) is a mycotoxin that results from the hydroxylation of the aflatoxin B1 (AFLAB1). It contaminates the milk of animals fed with a diet containing its precursor. In this work, we determined the occurrence of AFLAB1 and AFLAM1 in milk, as well as the chromatographic conditions to quantify these mycotoxins. The extraction and quantification of AFLAB1 and AFLAM1 in naturally contaminated and artificially spiked milk samples which are produced and marketed in the state of RS were performed using the AOAC official method and UHPLC with fluorescence detection. We obtained a separation factor of 2.3 for AFLAB1 and AFLAM1 using a mobile phase consisting of 1% acetic acid:acetonitrile:methanol (55:10:35). The analytical curves had a wide linearity range and the limit of quantification (LOQm) concentrations of AFLAB1 and AFLAM1 were equal to 0.5 and 0.25 μg L−1, respectively. Samples of pasteurized and ultra-high-temperature processed (UHT) milk showed natural contamination, and the levels for both aflatoxins ranged from 0.7 to 1.5 μg L−1. Raw and concentrated milk samples only contained AFLAM1, with a maximum average concentration of 1.7 μg L−1. These concentrations, higher than permitted by legislation, confirm the existence of a health risk, as well as highlight the relevance of searching for alternatives to reduce this contamination.

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