Selective spectrophotometric determination of paracetamol with sodium nitroprusside in pharmaceutical and biological samples

Abstract

A novel simple method to determine paracetamol with good selectivity has been established by using sodium nitroprusside as the chromogenic reagent. The experiment indicates that sodium nitroprusside can react with paracetamol in a basic solution to form a product with colored O-nitrosamines. The maximal absorption wavelength (λmax) and the apparent molar absorption coefficient of the product are 700 nm and 3.4 × 103 L/mol cm, respectively. A Good linear relationship is obtained between the absorbance and the concentration of paracetamol in a wide range of 0.19–96 μg/mL. The linear regression equation is A = 0.01695 + 0.02240C (μg/mL), with a correlation coefficient of 0.9993. The detection limit (3σ/κ) is 0.10 μg/mL, and the relative standard deviation (RSD) is 0.90% (n = 11). The parameters with regard to determination are optimized, and the reaction mechanism is discussed. The method has been successfully applied to the selective determination of paracetamol in pharmaceutical and biological samples.