钒金试剂Ⅱ指示滴定法测定天然水和岩矿中痕量金

Titration of Gold in Minerals,Rocks and Natural Waters by Using the New Indicator Vanadate-Auric Reagent Ⅱ

在硫磷混合酸和尿素存在下,用KI和SnCl_2还原富集在泡塑上Au^(3+)呈AuI而进入溶液。用NaNO_2氧化过量KI和SnCl_2,AuI中I^-不被氧化。过量NaNO_2被尿素破坏后,以作者合成的钒金试剂Ⅱ为指示剂,偏钒酸铵标准液滴定AuI中I^-,至溶液出现紫红色为终点测定痕量Au。在5ml滴定液中可检出0.3pgAu。对0.01ng Au,5次重复测定,其RSD为7.43％。

In acid solution vanadate-auric reagentⅡ can be oxidized by V ( Ⅴ ) , Au (Ⅲ ) , Ce ( Ⅳ ) , Cr ( Ⅵ ) and Mn ( Ⅶ), and a purple coloration is given. As low as 10-15 g/ml vanadate can be detected. The indicator has been applied successfully to the ammonium vanadate titrimetric determination of Au (0. 000001~200μg/g) in minerals and rocks and of Au(0. l^4000ng/L) in natural waters. The detection limit is 0. 3 pg Au in 5ml. The RSD for 5 determinations of 0.01 ng Auis 7.43%.