Positively charged sol-gel coatings for on-line preconcentration of amino acids in capillary electrophoresis.
Positively charged sol-gel coatings for on-line preconcentration of amino acids in capillary electrophoresis.
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DOI：
10.1021/ac0301696
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发表时间：
2004
影响因子：
7.4
通讯作者：
Wen Li;D. Fries;A. Alli;A. Malik
中科院分区：
文献类型：
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作者：
Wen Li;D. Fries;A. Alli;A. Malik
提出了一种新的在线提取和富集氨基酸的方法，使用溶胶-凝胶涂层柱耦合到传统的紫外/可见检测器。所提出的方法不需要对市售标准CE仪器进行任何额外的修改。在预浓缩程序中使用了提取、堆积和聚焦技术。通过在涂层溶胶溶液中使用N-十八烷基二甲基[3-（三甲氧基甲硅烷基）丙基]氯化铵（C18-TMS）来产生溶胶-凝胶涂层。由于C18-TMS中带正电荷的季铵部分的存在，所得溶胶-凝胶涂层携带正电荷。对于提取，适当调节样品的pH值以赋予氨基酸净负电荷。然后将样品的长塞通过溶胶-凝胶涂覆的毛细管，以通过带正电的溶胶-凝胶涂层和带负电的氨基酸分子之间的静电相互作用促进提取。提取的氨基酸的聚焦通过由局部pH变化进行的提取的氨基酸分子的解吸来完成。描述了两种不同的方法。这两种方法都表现出良好的萃取和富集效果。溶胶-凝胶涂层柱上获得的预浓缩结果进行了比较与CZE分析进行裸熔融石英柱与传统的样品注射。所述方法提供了150，000倍的丙氨酸富集效果。这两种方法在峰高和迁移时间方面均提供了可接受的重复性。
A novel on-line method is presented for the extraction and preconcentration of amino acids using a sol-gel-coated column coupled to a conventional UV/visible detector. The presented approach does not require any additional modification of the commercially available standard CE instrument. Extraction, stacking, and focusing techniques were used in the preconcentration procedures. Sol-gel coatings were created by using N-octadecyldimethyl[3-(trimethoxysilyl)propyl]ammonium chloride (C18-TMS) in the coating sol solutions. Due to the presence of a positively charged quaternary ammonium moiety in C18-TMS, the resulting sol-gel coating carried a positive charge. For extraction, the pH of the samples was properly adjusted to impart a net negative charge to amino acids. A long plug of the sample was then passed through the sol-gel-coated capillary to facilitate extraction via electrostatic interaction between the positively charged sol-gel coating and the negatively charged amino acid molecules. Focusing of the extracted amino acids was accomplished through desorption of the extracted amino acid molecules carried out by local pH change. Two different methods are described. Both methods showed excellent extraction and preconcentration effects. Preconcentration results obtained on sol-gel-coated columns were compared with the CZE analysis performed on bare fused-silica columns with traditional sample injections. The described procedure provided a 150,000-fold enrichment effect for alanine. The two methods provided acceptable repeatability in terms of both peak height and migration time.