SPECTROPHOTOMETRIC DETERMINATION OF PYRIDOXINE HYDROCHLORINE IN PHARMACEUTICAL PREPARATIONS AND FOODS

An easy and sensitive spectrophotometric assay of pyridoxine is descri bed. The procedure is based on formation of an azo dye by the reaction of pyridoxine with diazotized 2,4-dinitroaniline followed by the reac tion of the dye with Hg2+ ions to form a stable complex with maximum a bsorbance at 545 nm. The system obeys Beer's law for 475 mu g pyridoxi ne hydrochloride in an overall aqueous volume of 25 mt (correlation co efficient, 0.9998). On extraction into 5 mi, butan-1-ol, the system ob eys Beer's law in the range 0.8-15 mu g pyridoxine hydrochloride at 54 5 nm. The color is stable for 60 min in both aqueous and organic phase s (molar absorptivity, 3.7 x 10(4).L/mol.cm; coefficient of variation, 3.1%, n = 10). The pyridoxine contents of pharmaceutical preparations , a processed foodstuff, and 2 rice samples were determined by using t he proposed method. Assay reliability was established by recovery stud ies and parallel determination using a reported method.