Spectrophotometric Determination of Vitamin B1 in Dosage forms Using Drugs Compounds as Reagents by Normal and Reverse Flow Injection Methods

Background: Thiamine hydrochloride (THY), also known as vitamin B1, is a water soluble vitamin usually found in food, and considered as a dietary supplement and treatment in case of vitamin deficiency for example in malabsorption and chronic diarrhea. Objective: Rapid, green, and sensitive methods for the assay of vitamin B1 (thiamine hydrochloride, THY) in pharmaceutical forms, using normal and reverse flow injection manifolds and sulfonamide drugs as green and safe reagents were reported. Sulfamethoxazole and sulfadimidine drugs were used rather than toxic and expensive reagents. Methods: nFIA and rFIA manifolds were used for automated the reaction of THY with diazotized sulfamethoxazole (DSMZ) and diazotized sulfadimidine (DSDM) in an alkaline medium, respectively. The absorbance of the resultant red-orange azo dyes was monitored spectrophotometrically at λmax494 and 496nm for both methods, respectively. Results: The linearity of the suggested methods was in the ranges 2–80 µg/mL (LOD 0.69 µg/mL, % RSD 0.32, n=6) for nFIA method and 0.5-70 µg/mL (LOD 0.29 µg/mL, %RSD 0.85, n=6) for rFIA. Sampling frequency was 84 and 51 injections per hour for nFIA and rFIA methods respectively. Chemical and physical variables for both methods were studied carefully. Conclusion: Both flow injection modes were effectively applied in assay of THY in its pharmaceutical forms. The results were compared with those of standard pharmacopeia method and the statistical analysis indicated insignificant differences in accuracy and precision between the methods.