焦磷酸盐铜锡合金镀液中铜的分光光度法分析

Analysis of copper in pyrophosphate copper–tin alloy plating bath by spectrophotometry

为了克服EDTA容量法测定焦磷酸盐铜锡合金镀液中铜含量滴定终点不易判断的缺点,制定了分光光度法规程。在碱性条件下用三乙醇胺与铜离子反应生成稳定的蓝色配合物,以水做参比液,在波长680 nm处测定吸光度。镀液中的铁杂质与三乙醇胺生成无色配离子,不干扰铜的测定;镀液中的锡离子、锌杂质和铝杂质均无色,不影响测定;镀液中的焦磷酸钾、葡萄糖酸钠、酒石酸钾钠、氨基乙酸等配位剂对铜离子的配位能力较弱,不影响三乙醇胺与铜的配位反应。该法测定结果的相对平均偏差为0.65%,回收率为98.5%~101.2%。

The procedure for spectrophotometric analysis of copper content in a pyrophosphate copper-tin alloy plating bath was established to overcome the shortcoming that the end point is not easy to decide during EDTA volumetric analysis Copper ions react with triethanolamine, forming stable blue complexes under alkaline condition. The absorbance of the solution is determined at a wavelength of 680 nm with water as a reference. Iron impurities in the plating bath are masked by triethanolamine forming colorless complexes. Tin ions as well as zinc and aluminum impurities do not affect the determination due to their colorlessness. Potassium pyrophosphate, sodium gluconate, potassium sodium tartrate, glycine, and other complexing agent have no effect on the complexation reaction of copper with triethanolamine due to their weak complexation ability with copper ions. The method has a relative average deviation of 0.65% and a recovery ranging from 98.5% to 101.2%.