National Key Laboratory of Applied Organic Chemistry, Department of Chemistry, Lanzhou University, Lanzhou 730000, China.
J Chromatogr A. 2013 Apr 5;1284:188-93. doi: 10.1016/j.chroma.2013.02.006. Epub 2013 Feb 10.
A chiral recognition mechanism of ion-pair principle has been proposed in this study. It rationalized the enantioseparations of some basic analytes using the complex of di-n-butyl l-tartrate and boric acid as the chiral selector in methanolic background electrolytes (BGEs) by nonaqueous capillary electrophoresis (NACE). An approach of mass spectrometer (MS) directly confirmed that triethylamine promoted the formation of negatively charged di-n-butyl l-tartrate-boric acid complex chiral counter ion with a complex ratio of 2:1. And the negatively charged counter ion was the real chiral selector in the ion-pair principle enantioseparations. It was assumed that triethylamine should play its role by adjusting the apparent acidity (pH*) of the running buffer to a higher value. Consequently, the effects of various basic electrolytes including inorganic and organic ones on the enantioseparations in NACE were investigated. The results showed that most of the basic electrolytes tested were favorable for the enantioseparations of basic analytes using di-n-butyl l-tartrate-boric acid complex as the chiral ion-pair selector.
本研究提出了一种基于离子对原理的手性识别机制。它通过非水相毛细管电泳（NACE），利用二 - 正丁基 L-酒石酸和硼酸复合物作为手性选择剂，合理地解释了一些碱性分析物的对映体分离。质谱仪（MS）的方法直接证实，三乙胺促进了带负电荷的二 - 正丁基 L-酒石酸-硼酸复合物手性对映离子的形成，其复合物比为 2:1。带负电荷的对映离子是离子对原理对映体分离中的真正手性选择剂。据推测，三乙胺通过将运行缓冲液的表观酸度（pH*）调节到更高的值来发挥作用。因此，研究了各种基本电解质（包括无机和有机电解质）对 NACE 中对映体分离的影响。结果表明，大多数碱性电解质都有利于使用二 - 正丁基 L-酒石酸-硼酸复合物作为手性离子对选择剂对碱性分析物的对映体分离。
