Standard stock solution of AFM1 (1000 mg/L) was prepared by dissolving standard AFM1 (Pr. No.: A6428, Sigma–Aldrich, St. Louis, USA) in methanol (analytical grade; Kemika, Zagreb, Croatia). Working solutions for the enrichment of milk samples were prepared by further dissolution of stock solution in methanol up to a concentration of 10 μg/L. Stock solution was stored at 4 °C for no longer than 6 months, and working solutions were prepared before each analysis.