Fang Huaifang, Yang Fangxing, Sun Junling, Zeng Zhaorui, Xu Ying
Department of Chemistry, Wuhan University, Wuhan, People's Republic of China.
Electrophoresis. 2007 Oct;28(20):3697-704. doi: 10.1002/elps.200700210.
This paper describes a novel method that applies pressure-assisted field-amplified sample injection with reverse migrating micelles (PA-FASI-RMM) for the online concentration of neutral analytes in MEKC with a low-pH BGE. After injection of a plug of water into the separation capillary, negative voltage and positive pressure were simultaneously applied to initialize PA-FASI-RMM injection. The hydrodynamic flow generated by the positive pressure compensated the reverse EOF in the water plug and allowed the water plug to remain in the capillary during FASI with reverse migrating micelles (FASI-RMM) to obtain a much longer injection time than usual, which improved stacking efficiency greatly. Equations describing this injection mode were introduced and were supported by experimental results. For a 450-s online PA-FASI-RMM injection, three orders of magnitude sample enhancement in terms of peak area could be observed for the steroids and an achievement of detection limits was between 1 and 10 ng/mL.
本文描述了一种新颖的方法，该方法采用压力辅助场放大进样结合反向迁移胶束（PA-FASI-RMM），用于在低pH值背景电解质的MEKC中对中性分析物进行在线富集。在向分离毛细管中注入一段水塞后，同时施加负电压和正压力以启动PA-FASI-RMM进样。正压力产生的流体动力流补偿了水塞中的反向电渗流，并使水塞在采用反向迁移胶束的场放大进样（FASI-RMM）过程中保留在毛细管中，从而获得比平常长得多的进样时间，这极大地提高了富集效率。文中介绍了描述这种进样模式的方程，并得到了实验结果的支持。对于450秒的在线PA-FASI-RMM进样，类固醇的峰面积可实现三个数量级的样品增强，检测限达到1至10 ng/mL。
