Determination of Soluble Vitamins in Beverages

As an additional check, the determined values (DV) of vitamins A and E were compared to the label claim. Brand A claimed to provide 10% of the DV of vitamin E per serving, and brand B claimed 20% of the DV of vitamin E. In this study, we determined 15% and 25% of vitamin E in Brands A and B, respectively. Brand C claimed 10% each of vitamins A and E. The determined amounts were 10% each, based on FDA guidelines for nutritional labels. In the absence of a formulated aqueous-soluble mixture of the lipophilic vitamins, these results agree well with the label claim and show suitability of the method to determine these vitamins in beverages.

This work demonstrates that a single HPLC method using minimal sample preparation could be used to determine water- and fat-soluble vitamins in an enhanced water sample with high reproducibility. This was possible because of a polar-embedded stationary phase that allowed a gradient of 100% to 0% aqueous mobile phase without loss of column efficiency. Additionally, this separation method is compatible with mass spectrometry, allowing for a complementary detection method.

This single-method determination of both water- and fat-soluble vitamins has good linearity, precision, recovery, and limits of quantitation. ■

Hurum is a staff chemist, De Borba is applications laboratory supervisor, and Rohrer is director of corporate applications development, all at Dionex Corporation. For more information, contact Hurum at [email protected] or (408) 491-4295.

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