Qin Wei-Hua, Cao Cheng-Xi, Li Shan, Zhang Wei, Liu Wei
Laboratory of Analytical Biochemistry & Bioseparation, School of Life Science and Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Minhang, 200240 Shanghai, China.
Electrophoresis. 2005 Aug;26(16):3113-24. doi: 10.1002/elps.200400010.
The paper advanced the theoretical procedures for quantitative design on selective stacking of zwitterions in full capillary sample matrix by a cathodic-direction moving reaction boundary (MRB) in capillary electrophoresis (CE) under control of electroosmotic flow (EOF). With the procedures, we conducted the theoretical computations on the selective stacking of two test analytes of L-histidine (His) and L-tryptophan (Trp) by the MRB created with 30 mM pH 3.0 formic acid-NaOH buffer and 2-80 mM sodium formate. The results revealed the following three predictions. At first, the MRB cannot stack His and Trp plugs if less than 12.5 mM sodium formate is used to form the MRB and prepare the sample matrix. Second, the MRB can stack His and/or Trp sample plugs completely if higher than 50 mM sodium formate is chosen to form the MRB. Third, the MRB can only focus His plug completely, but stack Trp plug partially if 20-50 mM sodium formate is used; this implied the complete MRB-induced selective stacking to His rather than Trp. All the three predictions were quantitatively proved by the experiments. With great dilution of sample matrix and control of EOF, controllable, simultaneous and MRB-induced selective stacking and separation of zwitterions were achieved. The theoretical results hold evident significances to the quantitative design of selective stacking conditions and the increase of detection sensitivity of zwitterions in CE. In addition, the control of EOF by cetyltrimethylammonium bromide (CTAB) can evidently improve the stacking efficiency to both His and Trp.
本文提出了在毛细管电泳（CE）中，在电渗流（EOF）控制下，通过阴极方向移动反应边界（MRB）对全毛细管样品基质中的两性离子进行选择性堆积的定量设计理论程序。利用这些程序，我们对L-组氨酸（His）和L-色氨酸（Trp）这两种测试分析物，通过用30 mM pH 3.0甲酸-NaOH缓冲液和2-80 mM甲酸钠形成的MRB进行选择性堆积进行了理论计算。结果揭示了以下三个预测。首先，如果使用少于12.5 mM的甲酸钠来形成MRB并制备样品基质，MRB不能堆积His和Trp塞子。其次，如果选择高于50 mM的甲酸钠来形成MRB，MRB可以完全堆积His和/或Trp样品塞子。第三，如果使用20-50 mM的甲酸钠，MRB只能完全聚焦His塞子，但只能部分堆积Trp塞子；这意味着MRB诱导的对His而非Trp的完全选择性堆积。所有这三个预测都通过实验得到了定量证明。通过对样品基质的极大稀释和EOF的控制，实现了两性离子的可控、同时且由MRB诱导的选择性堆积和分离。理论结果对CE中选择性堆积条件的定量设计以及两性离子检测灵敏度的提高具有明显意义。此外，可以通过十六烷基三甲基溴化铵（CTAB）对EOF的控制，显著提高对His和Trp的堆积效率。
