Determination of Acetylcysteine in Pharmaceutical Samples by Silicomolybdenum Blue Spectrophotometry

An accurate and fast spectrophotometric method for the determination of acetylcysteine by silicomolybdenum blue has been established. The various effect factors on the determination of acetylcysteine by silicomolybdenum blue spectrophotometry are investigated in detail. The results show that under the optimum reaction conditions, SiO32- reacts with Mo7O246- to form silicon molybdenum heteropoly acid (H4Si(Mo3O10)(4)). Then H4Si(Mo3O10)(4) is reduced by hydrosulfuryl (-SH) in acetylcysteine to form silicomolybdenum blue (H4Si(Mo3O10)(2)(Mo3O9)(2)). The absorbance of silicomolybdenum blue is measured at the maximal absorption wavelength of 735 nm, and the content of acetylcysteine can be calculated based on this absorbance. A good linear relationship is obtained between the absorbance of silicomolybdenum blue and the concentration of acetylcysteine in the range of 5.040 similar to 25.20 mu g.mL(-1). The linear regression equation is A = 0.0272 + 21.484C (mg.mL(-1)), with a linear correlation coefficient of 0.9995. This proposed method has been successfully applied to the determination of acetylcysteine in pharmaceutical samples, and the results agree well with those obtained by pharmacopoeial method.