应用四甲基氢氧化铵控制电渗流的毛细管电泳方法分离多沙唑嗪及其中间体的对映体

建立了毛细管电泳手性分离多沙唑嗪中间体对映体的方法,并同时分离了多沙唑嗪对映体。考察了不同种类季铵盐对电渗流及分离的影响,其中四甲基氢氧化铵(TMB)能有效控制电渗流并提高组分的分离度。实验还考察了其他因素,如pH值、分离电压和磷酸二氢钠浓度对分离的影响。所用的毛细管为40 cm(有效长度30 cm)×50 μm,缓冲液为12 mmol/L β-环糊精、30 mmol/L TMB、60 mmol/L 磷酸二氢钠(pH 2.2),分离电压为20 kV。在此条件下多沙唑嗪及其中间体的对映体均达到了基线分离。实验结果表明,一些用β-环糊精不能完全分离的对映体通过加入TMB控制电渗流能达到满意的分离效果。

Chiral Separation of Doxazosin and Its Intermediate by Capillary Electrophoresis Using Tetramethylammonium Hydroxide to Control Electroosmotic Flow

A capillary electrophoretic method for the enantiomeric separations of doxazosin and its intermediate was developed. Several tetraalkylammonium reagents were examined for controlling the electroosmotic flow in order to improve resolution of the enantiomers. Tetramethylammonium hydroxide (TMB) was found more suitable than tetrabutylammonium hydroxide (TAB) or hexadecyltrimethylammonium bromide (CTAB) for the enantiomer separation. In addition, the effects of the pH value, the separation voltage and the concentration of the sodiumdihydrogen phosphate on the chiral separation were investigated. A buffer containing 60 mmol/L sodium dihydrogen phosphate (pH 2.2), 30 mmol/L TMB and 12 mmol/L beta-cyclodextrin (beta-CD) resulted in the baseline separation of the doxazosin enantiomers and its intermediate enantiomers. It showed that the presence of TMB was essential in some chiral separations that were previously not achieved by only using the beta-CD as a chiral selector.