Spectrophotometric Assay of Pyridoxine Hydrochloride (Vitamin B6) in Pharmaceutical Preparations and Serum Via Arsenazo III- Cerium (III) Reaction

A simple, rapid, accurate and precise spectrophotometric method is proposed for determination of pyridoxine hydrochloride (Vitamin B6) in pure form and in its pharmaceutical preparations and serum. The method is based on the oxidation-reduction reaction between vitamin B6 and cerium (IV) ion (ceric ion), then the subsequent reaction of cerium (III) with arsenazo III reagent in acidic medium in the presence of the neutral surfactant (Triton X-100) to produce a green complex which is stable, water soluble and has a maximum absorption at 716 nm with a molar absorptivity of 1.12105 l.mol-1.cm-1. Beers law is obeyed in the concentration range of 1 to 14 g of vitamin B6 in a final volume of 25 ml. The proposed method has been applied successfully to the assay of pyridoxine hydrochloride in pharmaceutical preparations and serum.