Determination of Aflatoxins in Yogurt by Dispersive Liquid-Liquid Microextraction and HPLC with Photo-Induced Fluorescence Detection

A high-performance liquid chromatography (HPLC) method with fluorescence detection for the determination of aflatoxins B1, B2, G1, G2, and M1 in yogurt using dispersive liquid-liquid microextraction as alternative sample treatment has been developed. To enhance the fluorescence of aflatoxins B1 and G1, a post-column photochemical derivatization has been proposed, avoiding the use of derivatization reagents. The method was validated using natural yogurt as representative matrix, showing a good linearity in the studied range (25-500 ng kg(-1)) and limits of quantification below the maximum level established by European Union in milk for the manufacture of milk-based products. Satisfactory recoveries ranging from 69.4 to 99.7 %, with relative standard deviations lower than 11.2 %, were obtained for all the compounds. The proposed method is simple, rapid, with low solvent consumption, inexpensive, and environmentally friendly.