锌(Ⅱ)-硫氰酸铵-亚甲蓝缔合体系褪色光度法测定痕量锌

来源期刊：冶金分析2010年第6期

论文作者：李人宇 李咏梅 卢洋 黄勇波

文章页码：41 - 44

关键词：褪色光度法； 锌； 硫氰酸铵； 亚甲蓝； β-环糊精； 聚乙烯醇； 离子缔合物

Key words：fading spectrophotometry； zinc； ammonium thiocyanate； methylene blue； β-cyclodextrin； polyvinyl alcohol； ion-association complex

摘    要：β-环糊精和聚乙烯醇存在下,在pH4.5 NaAc-HAc缓冲溶液中,Zn²⁺与硫氰酸铵和亚甲蓝(MB)反应生成稳定的离子缔合物[MB]₄[Zn(SCN)₆],使MB褪色,据此建立了褪色光度法测定痕量锌的新方法。体系的最大褪色波长为668nm,褪色程度与Zn2+浓度在2.77～160μg/L范围内呈线性关系,表观摩尔吸光系数为1.85×10⁵ L·mol^-1·cm^-1。采用巯基棉分离富集,测定了海水和管网水中痕量锌,相对标准偏差分别为1.0%和0.8%(n=5),回收率分别为98%和99%。

Abstract: A new fading spectrophotometric method was developed for the determination of trace zinc. In the presence of β-cyclodextrin and polyvinyl alcohol, Zn²⁺ reacted with ammonium thiocyanate and methylene blue (MB) to form a stable ion-association complex [MB]₄[Zn(SCN)₆] in NaAc-HAc buffer solution at pH 4.5, which led to the fading of MB. The maximum fading wavelength located at 668 nm. The fading degree of the system was linear with the concentration of Zn2+ in the range of 2.77-160 μg/L. The apparent molar absorption coefficient was 1.85×10⁵ L·mol^-1·cm^-1. The method has been applied to the determination of zinc in seawater and tap water after enrichment and separation with thiohydroxy cotton fiber, with the RSDs of 1.0% and 0.8% and the recoveries of 98% and 99%, respectively.