镀镍溶液中杂质量铅的快速测定

RAPID DETERMINATION OF IMPURITY LEAD IN Ni PLATING BATH

大量镍存在下测定微量铅是十分困难的,须要进行繁复的共沉淀分离及有机溶剂萃取操作,还要使用有毒的氰化物试剂。本文提出在铅-偶氮胂(Ⅲ)二元络合物的基础上,加入易形成多核络合物的高价钼离子,在偶氮胂Ⅲ相互对称的两侧进行络合反应而形成铅-钼-偶氮胂Ⅲ异金属双核三元络合物。它的最大吸收峰位于660nm,灵敏度高、稳定性好。特别是选择性十分优越,在钼酸铵存在下,许多金属离子均可形成钼杂多酸而被掩蔽。镍高至80毫克,锌高至100毫克对测定并无干扰。这确实是难能可贵的。用本法可测定镀镍溶液中的微量铅,可不作任何化学分离或溶剂萃取操作。

It is very difficult to determine trace amount of lead in the presence of a large amount of Ni. Complicated codeposit separation and extraction with organic solvents are needed, morover, the toxic cyanide reagant must be used. It is suggested that, on the basis of lead-azoarsine (III) dicomplex compound, if high valence molybdenum ions, which are liable to form polynuclear complex compound, is added, the complexing reaction will be carried out on both sides of symmetical azoarsine (IIl) and different metal dinuclear tricomplex compound Pb-Mo-azoarsine (III) is formed, Its max. absorption peak is at 660nm, with high sensitivity and good stability, esp, its selectivity is excellent. In the presence of ammonium molybdate, many metal ions can be formed into molybdenum heteropoly acid and masked. It is a rare color reagent since there is no interference on determination even when Ni gets to 80mg and Pb to 100mg. This method can be used to determine trace amount of Pb in Ni plating solution, without any chemical separation or solvent extraction