百里香酚蓝光度法测定水中痕量锌(II)

在邻苯二甲酸氢钾缓冲溶液中,聚氧乙烯特辛基酚醚(TritonX-100)微乳液存在下,百里香酚蓝与锌(II)形成稳定的橙黄色络合物,据此建立了分光光度法测定锌(II)的方法。实验表明,当络合物最大吸收波长为540nm时,锌(II)质量浓度在0.1~0.7mg/L范围内符合比尔定律,相关系数为0.9980。方法检出限为0.01mg/L,表观摩尔吸光系数为7.4×10⁴ L·moL^-1·cm^-1。加入柠檬酸钠-酒石酸钾钠混合掩蔽剂掩蔽Fe³⁺、Al³⁺,加入铜试剂掩蔽Cu²⁺、Cd²⁺、Pb²⁺。方法用于水中痕量锌(II)的测定,相对标准偏差(RSD,n=6)为1.6%和3.4%,加标回收率为98%和105%,测定值与原子吸收光谱法(AAS)基本一致。

Determination of trace zinc(II) in water by thymol blue spectrophotometry

Thymol blue could react with zinc(II) to form stable orange-yellow complex in potassium acid phthalate buffer solution in presence of Triton X-100 microemulsion. Thus the determination method of zinc(II) by spectrophotometry was established. The results showed that the maximum absorption wavelength of complex was 540nm. The beer′s law was obeyed with correlation coefficient of 0.9980 when the mass fraction of zinc(II) was in range of 0.1-0.7mg/L. The detection limit was 0.01mg/L. The apparent molar absorptivity was 7.4×10⁴ L·moL^-1·cm^-1. The sodium citrate-sodium potassium tartrate mixture was added to mask Fe³⁺ and Al³⁺. The copper reagent was added to mask Cu²⁺, Cd²⁺ and Pb²⁺. The proposed method was applied to the determination of trace zinc(II) in water. The relative standard deviation (RSD, n=6) was 1.6% and 3.4%, and the recovery was 98% and 105%, respectively. The found results were consistent with those obtained by atomic absorption spectrometry (AAS).