Validated Spectrophotometric Method to Assay of B 6 and B 3 Vitamins in Pharmaceutical Forms Using Potassium Iodide and Potassium Iodate

Abstract

A simple, precise and reliable spectrophotometric method for the determination of pyridoxine hydrochloride (vitB 6 ) and nicotinamide (vitB 3 ) in pure form and pharmaceutical formulations has been described. The method is based on the reaction of studied vitamin with a mixture of potassium iodide and potassium iodate in aqueous medium at (250.5 o C) to form yellow colored tri iodide ions (I3-). The reaction is followed spectrophotometrically by measuring the absorbance at 290, 335 and 288, 350 nm for vitB 6 and vitB 3 respectively. Beer's law was obeyed in the range of 0.5-20.0 μg mL -1 for all procedures. Molar absorptivities were found to be 1.49×10 4 , 1.93×10 4 and 0.89×10 4 , 1.25×10 4 L mol -1 cm -1 , for determination of vitB 6 and vitB 3 at 290, 335 and 288, 350 nm respectively. The proposed method has been applied to determine the components in commercial forms with no interference from the excipients. A comparative study between the suggested procedures and the official methods showed no significant difference between the two methods.