Spectrophotometric Determination of hiamin Hydrochloride in Pharmaceutical Preparations by Azo-Coupling Reactions with Sulphacetamide Sodium Reagent.

A simple, accurate and sensitive spectrophotometric method for the determination of Thiamin Hydrochloride (THH) in aqueous solution has been proposed . The method is based on coupling of thiamine hydrochloride with diazotized sulphacetamide sodium (SUD) in alkaline medium and in presence of cetyltrimthylammumonium bromide (CTAB) to form a pink water- soluble dye that is stable and has maximum absorption at 512nm. The molar absorptivity and Sandells sensitivity values of the formed dye were 1.36×10⁴-L.mol1-1.cm, 0.02479 μg.cm-1 respectively. Beer's law is obeyed in the concentration range (0.5-40μg.mL-1). The linear regression coefficients values were a=0.0404, b=-0.0137, and r2=0.9985 calculated for the general equation of the calibration curve (y=ax+b). The limit of detection (LOD) and limit of quantification (LOQ) were found to be (0.135 and 0.452μg.mL-1) respectively. The method has been successfully applied to the determination of thiamine hydrochloride in pharmaceutical formulations as tablets & injections.