Mouhammed Khateeb, Basheer Elias, Fatema Al Rahal, Validated Spectrophotometric Method to Assay of B6 and B3 Vitamins in Pharmaceutical Forms Using Potassium Iodide and Potassium Iodate, Volume 60, International Letters of Chemistry, Physics and Astronomy (Volume 60)
    A simple, precise and reliable spectrophotometric method for the determination of pyridoxine hydrochloride (vitB<sub>6</sub>) and nicotinamide (vitB<sub>3</sub>) 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<sup>o</sup>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<sub>6</sub> and vitB<sub>3</sub> respectively. Beer's law was obeyed in the range of 0.5-20.0 μg mL<sup>-1</sup> for all procedures. Molar absorptivities were found to be 1.49×10<sup>4</sup>, 1.93×10<sup>4</sup> and 0.89×10<sup>4</sup>, 1.25×10<sup>4</sup> L mol<sup>-1</sup> cm<sup>-1</sup>, for determination of vitB<sub>6</sub> and vitB<sub>3</sub> 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.
    Nicotinamide, Pharmaceutical Formulations, Potassium Iodate, Potassium Iodide, Pyridoxine Hydrochloride, Spectrophotometry