硅钼蓝分光光度法测定三氧化二砷中二氧化硅

Silicon molybdenum blue spectrophotometric determination of silicon dioxide in arsenic trioxide

研究了在三氧化二砷中加入盐酸,加热除砷,所得残渣用氢氧化钠溶解,硝酸酸化后,以钼酸铵为显色剂,在pH 0.9条件下,硅与钼酸盐形成硅钼黄络合物,用硫酸提高酸度,以抗坏血酸为还原剂,使硅形成稳定的硅钼蓝络合物,采用分光光度法测定其中的二氧化硅含量。硅钼蓝络合物最大吸收波长位于813nm处。本法相对标准偏差(RSD)为1.6%～1.9%(n=6),测定结果与ICP-AES法的结果相一致。

In this study,hydrochloric acid was added into arsenic trioxide to remove arsenic by heating.The obtained residual was dissolved with sodium hydroxide.After acidification with nitric acid,silicon could form silicon molybdenum yellow complex with molybdate at pH 0.9 using ammonium molybdate as color developer.With sulfuric acid increase the acidity,the complex was reduced to silicon molybdenum blue complex by ascorbic acid.The content of silicon dioxide was determined by spectrophotometry.The maximum absorption wavelength of silicon molybdenum blue complex was 813 nm.The relative standard deviations（RSD,n=6） were 1.6 %-1.9 %.The determination results of this method were consistent with those obtained by ICP-AES.