High performance liquid cromatography was employed to analyze the amount of thiamin, riboflavin and piridoxin in dried, pasteurized and sterilized milks. The vitamins were extracted with tricloroacetic acid 5%, remaining under ultrassonic vibration for one hour. They were analysed simultaneously, through C18 column, mobile phase composed by water:acetonitrile:NH4OH, containing 0.95g of hexanossulfonic acid. The final pH was ajusted to 3.6, 1.5 mL flow. The thiamin and riboflavin were analysed by UV a detector and the pyridoxin by a fluorescence detector. The low values of thiamin made its quantitation difficult, mainly in pasteurized milk. The detector of fluorescence contributed to the detection of pyridoxin in most of the analysed milks. The riboflavin, in its turn, found in higher values, could be analysed in all samples. The thiamin was found in higher values than the values declared in the labels of some brands of dried milk and the riboflavin was found with values below the declared values in one brand. In some brands of dried and sterilized milk, pyridoxin was found with values below the declared values.
milk; thiamin; riboflavin; pyridoxin; liquid chromatography
