Simple and sensitive spectrophotometric method for the determination of thiamine (VB1) in pharmaceutical formulations has been reported. The proposed method is based on the reaction between the (VB1) and sodium 1,2-naphthoquine-4-sulphonate (NQS) at alkaline medium (pH 11) to form deep brown product. Beer’s law is obeyed in the range 10-40 μg/ml of thiamine at maximum wavelength of 487 nm. Under optimized reaction conditions, linear regression equation of the calibration curve is: A= 0.022x + 0.171 (μg/ml) with a linear correlation coefficient of 0.997.
The limit of detection (LOD) and limit of quantification (LOQ) were found to be 1.71 μg/mL and 5.18 μg/ml respectively. The method has been successfully applied to the determination of thiamine (VB1) in pharmaceutical formulations, and can be used as a replacement of the existing sophisticated method used in quality control laboratories.