金对原子荧光法测汞化学干扰机理的实验研究

Experimental Study on the Mechanism of Chemical Interference Gold with Mercury by AFS

首次提出了KBH4和SnCl2分别作还原剂时金对原子荧光法测汞的干扰机理。在液相中,KBH4还原汞(Ⅱ)生成单质汞的过程中伴随金(Ⅲ)被还原为单质的同步化学反应,金汞共沉淀(形成金汞齐)是形成液相化学干扰的主要原因;加入氧化剂如KMnO4可以减缓金的干扰,但不能完全消除干扰。SnCl2作还原剂时汞(Ⅱ)经过两步反应生成单质汞,而金(Ⅲ)一步还原为单质,两个反应产物的形成过程存在化学动力学差异,从而克服了金对汞蒸气生成过程的液相化学干扰。

It＇s reported that the contrast of the mechanism between KBH4 and SnC12 was used as reductant at first, in the determination of Hg by AFS with Au. On condition that KBH4 as is reductant in the solution, Hg^2＋ was deoxidized and turned into Hg,at the same time Au^3＋ turned into Au, the concurrence of oxidation-deoxidization reactions upwards, mercuryamalgam was formed as soon as, that was the main interference factor to Hg in the solution.if the oxidant is added, for instance KMnO4, the interference could be decreased, but could not be cleared. The experiment result demonstrated that Au have no interference to assay of Hg by AFS in SnCl2 as is reductant. The reason that this difference of the kinetics chemical reaction, the process of Au^3＋ turned into Au was slower than that the process of Hg^2＋ turned into Hg.