赖氨酸-甲醇-1,2-萘醌-4-磺酸钠体系褪色光度法测定甲醇

Decolouring Spectrophotometric Determination of Methanol in Lysine-Methanol-Sodium 1,2-Naphthoquinone-4-sulfonate System

赖氨酸与1,2-萘醌-4-磺酸钠在碱性条件下发生亲核取代反应,生成红褐色的产物,在该体系中加入甲醇后发生褪色反应,褪色最大波长λmax=559 nm,甲醇质量浓度在0.050~7.61 g/L范围内与吸光度降低程度呈良好线性关系,线性回归方程为A=-0.005 17-0.086 79c（g/L）,线性相关系数r=0.999 6,检测限为49.5 mg/L,平均回收率为99.1%~102.6%。用于甲醇样品测定,结果满意。

A simple decolouring spectrophotometric method for the determination of methanol was developed in this work.A russety product can be formed by the reaction between Lysine（Lys） and sodium 1,2-naphthoquinone-4-sulfonate（NQS） in an alkaline solution.When methanol was added to the solution,the system involves decolouring process.Beer′s law is held in a range of methanol concentration of 0.050~7.61 g/L at a maximal decolouring wavelength of 559 nm.The equation of linear regression is A=-0.00517-0.086 79c（g/L）,with a linearly correlation coefficient of 0.999 6.The detection limit of methanol is 49.5 mg/L（3σ） and the recovery rate is in a range of 99.1%~102.6%.Analytical results obtained with this method are satisfactory.