应用压力辅助电动进样（ pressure?assisted electrokinetic injection， PAEKI）技术开发了毛细管电泳（ CE）对阳离子手性药物西酞普兰（ citalopram， CIT）拆分的高灵敏度分析方法。在电动进样（ electrokinetic injection， EKI）过程中，由于CIT的两个对映异构体与手性选择试剂（ sulfated?β?cyclodextrin， S?β?CD）之间的动态平衡常数存在差异而导致了电动歧视效应。因此，在EKI过程前向毛细管中充满不含手性选择剂的背景电解质，从而抑制电动进样歧视。通过两个步骤优化PAEKI过程中的关键参数得到电渗流和反向压力之间的平衡条件。在最优的PAEKI条件下（＋10 kV，0?2 psi（约1?4 kPa）），两个对映异构体在205 nm紫外检测条件下的检出限（ LOD；S／N＝3）达到1?1和2?2 ng／mL。灵敏度较常规的压力进样平均提高了62倍，方法的检测灵敏度达到了ng／mL （ ppb），有望成为检测人体体液中CIT对映异构体的有效方法。
Pressure?assisted electrokinetic injection ( PAEKI) was applied to the highly sensitive enantiosepara?tion of the positively charged drug citalopram ( CIT) by capillary electrophoresis ( CE) . It was found that the in?jection discrimination occurred in electrokinetic injection ( EKI) process due to the different dynamic equilibri?um constant between chiral selector ( sulfated?β?cyclodextrin, S?β?CD) and two isomers of CIT. Herein, it was proposed to use the background electrolyte ( BGE) without chiral selector to fill the capillary, and then start the EKI step to eliminate the injection discrimination of free analytes. The critical parameters in PAEKI could be optimized in two steps to seek the balance between the electroosmotic flow ( EOF ) and the counterbalance pressure. Under the optimized PAEKI conditions (+10 kV, 0?2 psi ( ca. 1?4 kPa) ) , the obtained LODs ( S/N=3) of the two isomers were 1?1 and 2?2 ng/mL under UV detection ( 205 nm) , which was averaged 62?fold im?proved in comparison with normal hydrodynamic injection ( HDI) . The proposal offered ng/mL ( ppb) level sen?sitivity of CIT determination and could be an effective method in the applications in human body biofluids.
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