Comparative assessment of high-performance liquid chromatographic methods for the determination of ascorbic acid and thiamin in foods

Abstract

A comparative assessment of HPLC methods for vitamin analysis was designed in which a number of institutions were asked to carry out the determination of ascorbic acid and thiamin in three samples (1, a mixture of thiamin and ascorbic acid in glucose; and 2 and 3, fortified breakfast cereals). Coefficients of variation between laboratories for sample 1 (ascorbic acid 5.6 and thiamin 6.9%) were much lower than for samples 2 and 3 (ascorbic acid 23 and 19% and thiamin 47 and 34%, respectively), the latter being considerably greater than is desirable. It is concluded that HPLC will not become a widely accepted technique for the determination of vitamins in foods until all the stages of the analysis, including extraction, clean-up and HPLC, are thoroughly validated.