RESUMO
In this study, using a liquid-liquid microextraction method for pre-concentration trace amounts of aflatoxins, the amount of Aflatoxins B1 and B2 in powdered milk was determined. Determination of aflatoxins was done by using high-performance liquid chromatography coupled with fluorescent detector. Samples were extracted by immunoaffinity column [IAC] clean-up, and their eluents were used as dispersants of the subsequent DLLME, for further enrichment of aflatoxins. Various parameters [the type of elution solvent, the type and volume of extraction solvent and disperser solvent, extraction time and centrifugation time] that affect the efficiency of two steps were optimized. Under the optimum conditions, the calibrations for B1 and B2 were found to be linear in the range of 0.03-5.0 and 0.006-1.0 ng ml-1 with 0.98 and 0.99 coefficient of estimation [R2], respectively. The results showed that dispersive liquid-liquid microextraction combined with HPLC is a selective, simple, sensitive and effective analytical method for the pre-concentration and determination of ultra trace amounts of aflatoxins. The method is suggested for pre-concentration and determination of B1 and B2 aflatoxins in milk powder