All-enzymatic HPLC method for determination of individual and total contents of vitamin B(6) in foods.

Background: There is a need for a reliable and accurate method for quantification of each of the seven individual vitamin B(6) compounds including pyridoxine-β-glucoside in foods.

Objective: To determine pyridoxal (PL), pyridoxamine (PM), pyridoxine (PN), pyridoxal 5'-phosphate (PLP), pyridoxamine 5'-phosphate (PMP), pyridoxine 5'-phosphate (PNP), and pyridoxine-β-glucoside (PNG) in foods.

Design: By specific enzymatic treatment, each of the seven vitamin B(6) compounds was all converted into 4-pyridoxolactone, which is a highly fluorescent compound.

Development of simultaneous enzymatic assay method for all six individual vitamin B6 forms and pyridoxine-beta-glucoside.

A method for determining all of the six natural vitamin B(6) compounds and pyridoxine-beta-glucoside in urine from humans consuming their usual diet was developed. These compounds were specifically converted with 5 enzymes into a high fluorescent 4-pyridoxolactone which was supersensitively determined by an isocratic HPLC. All of the compounds in urine from humans consuming their usual diets were for the first time determined together.