Abstract
Natural vitamin B_6 consists of six compounds which are pyridoxine, pyridoxal, pyridoxamine, pyridoxine 5'-phosphate, pyridoxal 5'-phosphate, and pyridoxamine 5'-phosphate. They show the same nutritional efficiency. Plant-derived foods contain pyridoxine-β-glucoside, a storage form of vitamin B_6. These compounds have chemically distinct functional groups. Many methods have been developed to determine them. Current application status and characteristics of microbiological methods, spectroscopic, fluorometric, electrochemical, and capillary electrophoretic methods, and liquid chromatographic, including HPLC, methods are commented. Advantages and disadvantages of several sample preparation methods for analysis of vitamin B_6 compounds are also described. Finally, a principle and protocols of a challenging method, all enzymatic HPLC method, which is applicable for determination of the individual vitamin B_6 compounds and pyridoxine-β-glucoside, is described.
