毛细管电泳法间接检测茶水中金属离子

Separation and Determination of Metal Ions in Tea Water by Capillary Electrophoresis

本实验采用毛细管电泳间接紫外检测技术测定了西湖龙井茶中金属离子的质量浓度。实验研究了电解质组成,如络合剂、pH、间接紫外检测试剂和最佳测试条件。结果表明:最佳实验条件是采用压力进样(30mbar×5s),未涂层石英毛细管柱60um(id)×50cm,运行电压12KV,紫外检测波长210nm,柱温25℃,缓冲液为pH=4.82、含有浓度为6.0mmol/L咪唑的乙酸溶液。在实验条件下6分钟内实现K+、、Ca2+、Na+、Mg2+、Zn2+五种五种离子的分离和测定。迁移时间的相对标准偏差(RSD)<0.5%,峰面积RSD<5%(n=5),最低检测限依次为0.002mg/L、0.001mg/L、0.001mg/L、0.01mg/L、0.05mg/L。该方法用于茶水中金属离子的含量测定,回收率95.59%-102.93%%,实验得到了满意的结果。

Capillary zone electrophoresis （CZE） was used to determine metal cations in Longjing Tea 6mmol/L lmidazol solution was used as background electrolyte. 0. 2mol/L acetic acid was used as selectivity improvement reagent . In the condition of PH=4. 82. 12kV separation voltage and 25℃ column temperature and indirect iN （210um） was detected. The K^＋, Ca^2＋. Na^＋. Mg^2＋. Zn^2＋ were separated and determined in 6 minutes. Under the given conditions, the relative standard deviation of migration times was less than 0. 5% and that of peak area was less than 5%. The minimum detectable concentration were 0. 002mg/L, 0. 001mg/L, 0. 001mg/L, 0. 01mg/L, 0. 05mg/L. The results of determination of recovery in this method ranged from 95. 59%-102.93%. This method is convenient, rapid, sensitive and low cost.