title: Pressure-assisted electrokinetic injection stacking for citalopram drug to achieve highly sensitive detection and enantioseparation by capillary electrophoresis.
abstract: Pressure-assisted electrokinetic injection (PAEKI) was applied to the highly sensitive enantioseparation of the positively charged drug citalopram (CIT) by capillary electrophoresis (CE). It was found that the injection discrimination occurred in electrokinetic injection (EKI) process due to the different dynamic equilibrium 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 improved in comparison with normal hydrodynamic injection (HDI). The proposal offered ng/mL (ppb) level sensitivity of CIT determination and could be an effective method in the applications in human body biofluids.
authors.forename: Zhongqi
authors.initials: Z
authors.lastname: Xu
authors.forename: Feng
authors.initials: F
authors.lastname: Ye
authors.forename: Yongle
authors.initials: Y
authors.lastname: Wang
authors.forename: Aimei
authors.initials: A
authors.lastname: Li
mesh_terms: D015283:Citalopram / Q000032:analysis*; D004573:Electrolytes; D019075:Electrophoresis, Capillary; D007536:Isomerism; D057230:Limit of Detection; D011312:Pressure; D047392:beta-Cyclodextrins
chemical_list: D004573:Electrolytes; D047392:beta-Cyclodextrins; D015283:Citalopram; C031215:betadex