Liu Z, Otsuka K, Terabe S
Faculty of Science, Himeji Institute of Technology, Kamigori, Hyogo, Japan.
Electrophoresis. 2001 Oct;22(17):3791-7. doi: 10.1002/1522-2683(200109)22:17<3791::AID-ELPS3791>3.0.CO;2-F.
The feasibility of open-tubular capillary electrochromatography (OTCEC) with UV detector for quantitation of enantiomers is explored, and a simple on-line sample concentration method to improve detection sensitivity of negatively charged enantiomers more than 1000-fold is described. With a capillary of 25 microm ID, the limits of detection (LODs) for absolute concentration and for enantiomeric ratio are 10(-6) M and 0.6-0.8% (signal-to-noise ratio S/N = 10). Good linearity and reproducibility are observed. The detection sensitivity is enhanced by combination with field-enhanced sample injection (FESI). A water plug is introduced hydrodynamically into the capillary inlet end and then the sample solution prepared with water is introduced with electrokinetic injection. With this concentration technique, the LOD for absolute concentration is reduced to a 10(-9) M level. On the other hand, due to the peak-sharpening effect of FESI, the LOD for enantiomeric ratio for the first-eluted enantiomer is significantly improved, being 0.3%. Effects of the injection conditions, such as length of water plug, buffer concentration, injection voltage, and injection time on the enrichment efficiency are investigated. Online concentration of a racemic compound with two chiral centers is demonstrated.
探索了采用紫外检测器的开管毛细管电色谱法（OTCEC）用于对映体定量分析的可行性，并描述了一种简单的在线样品浓缩方法，该方法可将带负电荷对映体的检测灵敏度提高1000倍以上。使用内径为25微米的毛细管时，绝对浓度和对映体比例的检测限（LOD）分别为10^(-6) M和0.6 - 0.8%（信噪比S/N = 10）。观察到良好的线性和重现性。通过与场增强进样（FESI）相结合提高了检测灵敏度。通过流体动力学方法将水塞引入毛细管入口端，然后用电动力进样引入用水配制的样品溶液。采用这种浓缩技术，绝对浓度的检测限降低到10^(-9) M水平。另一方面，由于FESI的峰锐化效应，先洗脱对映体的对映体比例检测限显著提高，达到0.3%。研究了进样条件，如水塞长度、缓冲液浓度、进样电压和进样时间对富集效率的影响。展示了具有两个手性中心的外消旋化合物的在线浓缩。
