毛细管电泳法间接测定茶水、矿泉水中金属离子

采用毛细管电泳间接紫外检测技术测定了茶水、矿泉水中金属离子的含量.研究了电泳液组成和最佳实验条件.结果表明：采用pH=4.82含有浓度为6.0 mmol/L咪唑的乙酸缓冲液作为电泳液,压力进样（30 mbar×5 s）,未涂层石英毛细管柱75μm×50 cm,分离电压12 kV,检测波长210 nm,柱温为25℃实验条件下,6 min内实现K＋、Ca2＋、Na＋、Mg2＋、Zn2＋5种离子的分离和测定.保留时间的相对标准偏差（RSD）小于0.5%,峰面积RSD小于5%（n=7）,最低检测限依次为0.002、0.001、0.001、0.010和0.050 mg/L.该方法用于茶水、矿泉水中金属离子含量的测定,回收率95.6%-108.6%,结果良好.

Separation and Determination of Some Metal Ions in Tea and Mineral Water Using Capillary Electrophoresis

Capillary zone electrophoresis（CZE） was used to determine metal ions in Longjing Tea and Baiyan mineral water.6 mmol/L imidazol solution was used as the background electrolyte and 0.2 mol/L acetic acid was used as the selectivity improvement reagent.Under conditions of pH 4.82,12 kV separation voltage,25 ℃ column temperature and indirect UV（210 nm） detection,K＋,Ca2＋,Na＋,Mg2＋ and Zn2＋ were separated and determined within only 6 min.The relative standard deviations for retention times and peak areas were less than 0.5% and 5%（n=7）,respectively.The detection limits of K＋,Ca2＋,Na＋,Mg2＋ and Zn2＋ were 0.002,0.001,0.001,0.010 and 0.050 mg/L respectively.The recoveries of the metal ions in real samples were in the range of 95.6%-108.6%.