1. Addo, C. and Augustin, J. (1988) Changes in the vitamin B6 content in potatoes during storage. J. Fd Sci., 53, 749–52.
2. AOAC (1990a) Thiamine (vitamin B1) in milk-based infant formula. Fluorometric method. Final action 1962. In AOAC Official Methods of Analysis, 15th edn (ed. K. Helrich), Association of Official Analytical Chemists, Inc., Arlington, VA, 986.27.
3. AOAC (1990b) Niacin and niacinamide in drugs, food and feeds. Colorimetric method. Final action 1962. In AOAC Official Methods of Analysis, 15th edn (ed. K. Helrich), Association of Official Analytical Chemists, Inc., Arlington, VA, 961.14.
4. AOAC (1990c) Vitamin B6 (pyridoxine, pyridoxal, pyridoxamine) in food extracts. Microbiological method. Final action 1975. In AOAC Official Methods of Analysis, 15th edn (ed. K. Helrich), Association of Official Analytical Chemists, Inc., Arlington, VA, 961.15.
5. Association of Vitamin Chemists, Inc. (1966) Methods of Vitamin Assay, 3rd edn, Interscience Publishers, New York, pp. 197–208.