Zn（Ⅱ）－C_2O_4^（2－）－SAF－CTMAB体系的分光光度研究及应用

Spectrophotometric Study and Application on Colour Reaction of Tetrabasic Complex for Zn(Ⅱ)-C_2O_4￣(2-)-SAF-CTMAB System

研究了锌（Ⅱ）－草酸盐－水杨基荧光酮（ＳＡＦ）－溴化十六烷基三甲铵（ＣＴＭＡＢ）体系形成四元混配络合物的显色反应条件．在ｐＨ９．０的硼砂－ＨＣｌ缓冲溶液中，形成摩尔比为Ｚｎ（Ⅱ）：Ｃ２Ｏ４２－：ＳＡＦ：ＣＴＭＡＢ＝１：１：２：４的紫红色络合物，络合物的最大吸收彼长为λｍａｘ＝５６０ｎｍ、表观摩尔吸收系数ε５６０为１．１×１０５Ｌ·ｍｏｌ－１·ｃｍ－１，锌（Ⅱ）含量在０～８μｇ／２５ｍＬ范围符合比耳定律。显色２０ｍｉｎ后体系的吸光度值达最大，至少稳定３ｈ不变；方法用于测定大米粉、人发及含锌营养食盐中的微量锌（Ⅱ）、结果满意。

The conditions of the colour reaction of the Zn (Ⅱ)-oxalate-salicylfluronecetyltrimethylammonium bromide system for determining trace amounts of Zn(Ⅱ) have been studied, The result shows that in sodium tetraborate-hydrochloric acid buffer sloution fo pH from 8.30￣9.25,the soluble purple-red tetrabasic complex of Zn(Ⅱ)with C2CO-SAF-CTMAB is formed with the maximum absorption wavelength at 560 nm and the apparent molar absorption coefficient is 1.1 ×105L·mol-1. The Beer's law is obeyed in the concentration range of 0!8μg/25 mL for Zn(Ⅱ). The molar ratio in the complex has been estimated to be Zn(Ⅱ):C2CO:SAF:CTMAB=1:1:2:4. The method as been applied to the determination of trace Zn(Ⅱ) in rice powder, human hair and nutritive tabie salt of added Zn(Ⅱ) and the relative standard deviation is 3.2%, 2.4% nad 1.3%, respectively.