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近年来,国内外一些资料介绍了用二乙胺硫代甲酸银(Silver-Diethyldithiocarbamate,简称Ag-DDC)比色法测定矿石、水以及锗中的砷。该法的要点是在硫酸一碘化钾介质中,用氯化亚锡将砷还原为低价,然后用金属锌将低价砷全部还原为砷化氢。逸出的砷化氢气体用Ag—DDC的含少量有机碱类的氯仿溶液或Ag—DDC的吡啶溶液吸收。这时析出棕红色的胶状银,借此进行比色测定。其反应式为:
In recent years, some domestic and foreign information describes the use of silver diethyldithiocarbamate (Ag-DDC) colorimetric determination of ores, water and germanium in arsenic. The key point of this method is that arsenic is reduced to a low price by stannous chloride in a potassium iodate solution of sulfuric acid, and all the low-price arsenic is reduced to arsine by metallic zinc. The evolved arsine gas is absorbed in a solution of Ag-DDC in chloroform containing a small amount of organic base or in a pyridine solution of Ag-DDC. At this time precipitation of reddish colloidal silver, whereby the colorimetric determination. The reaction is: