Aflatoxin M1and ochratoxin A in a human milk bank in the city of São Paulo, Brazil

Abstract

Because infants are more susceptible to the adverse effects of mycotoxins, this work was carried out to determine aflatoxin M₁ (AFM₁) and ochratoxin A (OA) in milk from the Human Milk Bank of the Southern Regional Hospital, São Paulo, Brazil. Analytical methods were first established and evaluated. The methods involved the extraction of AFM₁ with methanol and OA with 1% aqueous sodium bicarbonate solution and methanol, clean-up with immunoaffinity columns having antibodies specific for each mycotoxin and quantification by high performance liquid chromatography (HPLC) with fluorescence detection. The method established for AFM₁ had mean recovery percentages of 94, 77 and 82% and coefficients of variation of 17.5, 3.4 and 4.2% at 0.01, 0.03 and 0.05 ng ml⁻¹, respectively. For the OA method, the corresponding values were 84, 84 and 75% for recovery and 14.1, 3.7 and 4.0% for the coefficient of variation. The limit of quantification for both methods was 0.01 ng ml⁻¹. Of a total of 50 samples analysed, only one was contaminated with AFM₁, at 0.024 ng ml⁻¹, and two with OA, at 0.011 and 0.024 ng ml⁻¹. Although the incidence observed was low, it is recommended that the study be extended to other milk banks of the city of São Paulo.