[HPLC method for determination of vitamin C in milk, whey and whey beverages]

A method is described for the estimation of L-ascorbic acid and L-dehydroascorbic acid in milk, whey, and whey drinks by paired-ion reversed-phase HPLC using a C18-column. L-ascorbic acid is detected UV-spectrophotometrically at 248 nm, L-dehydroascorbic acid is determined spectrofluorometrically with excitation at 350 nm and emission at 430 nm, after derivatisation into a quinoxaline fluorophor.