丽春红S褪色分光光度法测定溴酸根离子的研究

Study on the Fading Photometric Determination of Micro-amounts of Bromate with Ponceau S

在盐酸介质中,依据溴酸根离子氧化丽春红S褪色的原理提出了测定溴酸根离子的新方法,研究了测定的最佳条件。测定的最大吸收波长λmax为510 nm,溴酸根离子在0.5-5.0μg/mL范围内符合比尔定律,线性回归方程为A510=0.318 5ρ-0.040 6,相关系数为0.994 94,表观摩尔吸光系数为4.08×10^4L/（mol.cm）。该法可用于化学试剂中的微量溴酸根测定,结果满意。

A new photometric method for the determination of micro-amounts of bromate is proposed based on the oxidation of Ponceau S in HCl medium. The optimal conditions were studied. The maximum absorption of Ponceau S lies at 510 nm. A decrease of Ponceau S absorbance results from its oxidation by bromate, and a linear relationship is established between the decrease of absorbanee and bromate concentration of 0.5-5.0μg/mL. Beer＇s law is obeyed with the regression equation A510 =0. 318 5ρ-0. 040 6, the related coefficient 0. 994 94 and the Molar absorbance coefficient 4.08× 10^4 L/（mol · cm）. The proposed method has been applied to the determination of micro-amounts of bromate in chemical reagents with satisfactory results.