Abstract:

A rapid, simple and sensitive method for the determination of carbocisteine using sodium 1, 2-naphthoquinone-4-sulfonate is presented in this paper. The result indicated that in pH 11.00 buffer solution, carbocisteine can react with sodium 1, 2-naphthoquinone-4-sulfonate to form the russet product and the stoichiometric ratio of the product is 1:1. When tetradecyl benzyl dimethyl ammonium chloride is added to the above solution, the sensitivity of the coloration reaction between carbocisteine and sodium 1, 2-naphthoquinone-4-sulfonate is improved. Beer’s law is well obeyed in the range of carbocisteine concentrations of 0.72-28.7µg ml-1 at the maximum absorption of 466 nm (ε466 is 2.2 ×103L/ mol.cm). The equation of linear regression is A =0.22302+0.01198 C (mg/L), with a correlation coefficient of 0.9992. The limit of detection (3σ/κ) is 0.70mg /L, R.S.D. is 0.52%, and average recovery rate is in the range of 99.0--103.1%. This proposed method has been successfully applied to the determination of carbocisteine in pharmaceutical samples with satisfactory results.