Michalke B, Schramel P
GSF-National Research Centre for Environment and Health, Neuherberg, Germany.
J Chromatogr A. 1998 May 20;807(1):71-80. doi: 10.1016/s0021-9673(97)01231-4.
The high resolution potential of capillary electrophoresis (CE) makes CE techniques valuable for separations of selenium species, both, organic and inorganic. Such effective separations of charged species are possible using the CZE mode (Z = zone). Very powerful separations can be achieved by capillary isoelectric focusing, when analysing molecules showing different isoelectric points (pI) values, such as organic Se species. Inductively coupled plasma (ICP) MS is an element-specific multi-element detector, providing extremely low detection limits. The combination of CE with ICP-MS promises a powerful tool for metal speciation. Therefore, an online hyphenation of CE [using capillary zone electrophoresis (CZE) or capillary isoelectric focusing (cITP) model] with ICP-MS, which was developed earlier, was modified and applied to selenium speciation. Separation was differentiated from the detection step during hyphenation. This resulted in short separation times (10 min) and a subsequent detection step lasting 100 s. Firstly, a CZE method was applied, providing a separation of six Se species of interest in one run [Se(IV), Se(VI), selenium carrying glutathione (GSSeSG), selenomethionine (SeM), selenocystine (SeC), selenocystamine (SeCM)]. This CZE method used an alkaline background electrolyte (Na2CO3/NaOH). The Se species were separated sufficiently from each other. Detection limits were calculated as 10 or 20 micrograms Se l-1 for inorganic Se species and 30-50 micrograms Se l-1 for organic Se species. The method was applied to standard mixtures and body fluids like human milk and serum. Secondly, a cIEF separation (pH range 2-10) was employed for organic Se species only in parallel. Detection limits were around 10-30 micrograms Se l-1. The method was applied to standard mixtures and body fluids like human milk and serum.
毛细管电泳（CE）的高分辨率潜力使CE技术在分离有机和无机硒物种方面具有重要价值。使用CZE模式（Z = 区带）可以实现对带电物种的有效分离。当分析显示不同等电点（pI）值的分子，如有机硒物种时，毛细管等电聚焦可以实现非常强大的分离效果。电感耦合等离子体质谱（ICP）MS是一种元素特异性多元素检测器，具有极低的检测限。CE与ICP-MS的结合有望成为一种强大的金属形态分析工具。因此，对早期开发的CE（使用毛细管区带电泳（CZE）或毛细管等速电泳（cITP）模式）与ICP-MS的在线联用进行了改进，并应用于硒形态分析。在联用过程中，分离步骤与检测步骤区分开来。这使得分离时间缩短至10分钟，随后的检测步骤持续100秒。首先，应用了一种CZE方法，一次运行即可分离出六种感兴趣的硒物种[硒（IV）、硒（VI）、携带谷胱甘肽的硒（GSSeSG）、硒代蛋氨酸（SeM）、硒代胱氨酸（SeC）、硒代半胱胺（SeCM）]。该CZE方法使用碱性背景电解质（Na2CO3/NaOH）。这些硒物种彼此之间得到了充分分离。无机硒物种的检测限计算为10或20微克硒/升，有机硒物种的检测限为30 - 50微克硒/升。该方法应用于标准混合物以及人乳和血清等体液。其次，仅并行地对有机硒物种采用了cIEF分离（pH范围2 - 10）。检测限约为10 - 30微克硒/升。该方法也应用于标准混合物以及人乳和血清等体液。
