Abstract
Sequential injection analysis technique was utilized for automatic titration of vitamin C in drug formulation. The method is based on the oxidation reaction of vitamin C with potassium permanganate in sulfuric acid media. The titration reaction was monitored by the decrease of absorbance of the permanganate at its maximum wavelength at 525 nm. The super modified simplex computer program was successfully utilized for optimizing the reaction parameters such as sulfuric acid and potassium permanganate concentration as well as determining the stoichiometry of the reaction. The optimized operating conditions were 0.418 μmol/L potassium permanganate and 7.49 μmol/L sulfuric acid with the injection of 0.25 μmol/L vitamin C thus verifying the stoichiometry of 2:5:16 for permanganate, vitamin C and sulfuric acid respectively. In addition a (3f) factorial design was employed for studying interaction effects. The method was found to be applicable for the detection of vitamin C in the range between 100 to 350 ppm and it was found to be accurate when statistically compared with the BP standard method. The method exhibited no interferences from excepients added in drug formulation. The method was also found to be faster and more economical compared to the previous reported methods.
