[The determination of pyridoxine hydrochloride (vitamin B6) according to European Pharmacopoeia 4.0].

Determination of pyridoxine hydrochloride according to the European Pharmacopoeia 4.0 In the Ph.Eur. 4.0 assay pyridoxine hydrochloride is titrated by sodium hydroxide 0.1 mol x 1(-1) in ethanolic solution. The impossibility of a correct evaluation of the titration curve is shown both in theory and practice. The new method in Ph.Eur. 4.04 is an acidimetric titration of the base chloride. In a mixture of formic acid/acetic anhydride the titration is made by perchloric acid. Because some critical points in this assay an alternative method is developed. This method is robust and should give results with high accuracy.