8-羟基喹哪啶固相萃取光度法测定茶水中的微量铁

基于固相萃取分离技术结合分光光度法，建立了一种测定茶水中微量铁的分析方法。在pH为8．0的氯化氨一氨水缓冲溶液介质中，在十六烷基三甲基溴化铵（CTMAB）存在下，8一羟基喹哪啶与铁反应生成稳定的蓝紫色络合物，该络合物可被WatersSep-ParkC18固相萃取小柱萃取，用乙醇洗脱后用光度法测定，固相萃取柱不被破坏且可重新处理使用。在乙醇介质中，络合物的最大吸收波长为605nm，在此波长下其它金属离子的络合物无光吸收，对铁选择性很好，铁含量在0-5．0μg·mL。内符合比尔定律，检出限为0．052μg·mL^-1。方法操作简单、快速、结果正确可靠，应用于茶水中微量铁的测定，结果令人满意。

Determination of Trace Iron in Tea Water by Solid Phase Extraction Spectrophotometric Measuration with 8-Hydroxyquinadine

A new method of preconcentration and determination trace iron in tea water was developed using solid phase extraction of Sep-Pak C18 cartridge followed by spectrophotometry. In the presence ofpH 8.0 NH4C1-NH3 · H20 buffer solution and cetyltrimeth- ylammonium bromide （CTMAB） medium, 8-hydroxyquinaldine could react with the iron to form a stable blue purple complex. The complex could be extracted by solid phase extraction technique on Sep-Pak C18 cartridge and could be ehited from the cartridge with ethanol, then the eluant was determined by spectrophotometry and the structure of cartridge was kept well, which could be retreated and reused readily. In ethanol medium, the maximum absorption wavelength of the complex was 605nm, Beer＇s law was obeyed in the range of 0-5.0 μL g/mL of iron and the detection limit of the method were found to be 0.052 μL g/mL for iron. The method was simple, sensitive, results were accurate and reliable. It had been applied to the determination of trace iron in tea water with satisfac-tory results.