title: Head-column field-amplified sample stacking in a capillary electrophoresis-flow injection system.
abstract: A simple, effective, and continuous online concentration method for the sensitive detection of alkaloids applying CE-flow injection analysis with head-column field-amplified sample stacking was developed. A series of samples was continuously introduced into the capillary by electrokinetic means without interrupting the high voltage. A short water plug was introduced by the EOF at the capillary inlet end prior to sample introduction. Under optimum conditions, 15-fold improvement in concentration sensitivity was achieved, giving an LOD of about 0.67 and 0.73 microg/mL for ephedrine (E) and pseudoephedrine (PE), respectively. The separation could be achieved within 4 min and sample throughput rate could reach up to 7/h. The repeatability (defined as RSD) was 3.62, 1.51% with peak area evaluation and 1.30, 2.58% with peak height evaluation for E and PE, respectively. This method has been successfully applied to the analysis of commercial pharmaceutical preparations containing E and PE, and the recoveries were 92.3-102.4%.
authors.affiliation: Department of Chemistry, Lanzhou University, PR China.
authors.forename: Liuyin
authors.initials: L
authors.lastname: Fan
authors.forename: Yuqiao
authors.initials: Y
authors.lastname: Cheng
authors.forename: Yuqin
authors.initials: Y
authors.lastname: Li
authors.forename: Hongli
authors.initials: H
authors.lastname: Chen
authors.forename: Xingguo
authors.initials: X
authors.lastname: Chen
authors.forename: Zhide
authors.initials: Z
authors.lastname: Hu
mesh_terms: D001881:Borates; D002021:Buffers; D019075:Electrophoresis, Capillary / Q000295:instrumentation* / Q000379:methods*; D004809:Ephedrine / Q000302:isolation & purification; D006863:Hydrogen-Ion Concentration
chemical_list: D001881:Borates; D002021:Buffers; D004809:Ephedrine