Timerbaev A R, Semenova O P, Buchberger W, Bonn G K
Department of Analytical Chemistry, Johannes Kepler University, A-4040, Linz, Austria.
Anal Bioanal Chem. 1996 Feb;354(4):414-9. doi: 10.1007/s0021663540414.
A method for the simultaneous determination of chromium(III) and chromium(VI) by capillary electrophoresis (CE) has been developed. The chromium(III) has been chelated with 1,2-cyclohexanediaminetetraacetic acid (CDTA) in order to impart a negative charge and similar mobility to both the chromium(III) and the chromium(VI) species. The effects of the amount of the reagent, pH and heating time required to complete the complexation have been studied. Factors affecting the CE behaviour such as the polarity of electrodes and the pH of electrophoretic buffer have been investigated. The separated species have been monitored by direct UV measurements at 214 nm. The detection limits achieved are 10 microg/l for Cr(VI) and 5 microg/l for Cr(III) and linear detector response is observed up to 100 mg/l. The procedure has been applied to the determination of both chromium species in industrial electroplating samples and its accuracy was checked by comparing the results (as total chromium) with those of atomic absorption spectrometry. No interference occurred from transition metal impurities under optimized separation conditions. The method is also shown to be feasible for determining Cr(III) as well as other metal ions capable to form complexes with CDTA (like iron(III), copper(II), zinc(II) and manganese(II)) in pharmaceutical preparations of essential trace elements.
已开发出一种通过毛细管电泳（CE）同时测定铬（III）和铬（VI）的方法。铬（III）已与1,2 - 环己二胺四乙酸（CDTA）螯合，以使铬（III）和铬（VI）物种都带有负电荷并具有相似的迁移率。研究了试剂用量、pH值和完成络合所需的加热时间的影响。研究了影响CE行为的因素，如电极极性和电泳缓冲液的pH值。通过在214 nm处的直接紫外测量对分离出的物种进行监测。铬（VI）的检测限为10 μg/l，铬（III）的检测限为5 μg/l，在高达100 mg/l的浓度范围内观察到线性检测器响应。该方法已应用于工业电镀样品中两种铬物种的测定，并通过将结果（以总铬计）与原子吸收光谱法的结果进行比较来检验其准确性。在优化的分离条件下，过渡金属杂质没有产生干扰。该方法还被证明对于测定药用制剂中必需微量元素中的铬（III）以及其他能够与CDTA形成络合物的金属离子（如铁（III）、铜（II）、锌（II）和锰（II））是可行的。
