title: On-line concentration of neutral analytes by complexation and acetonitrile sweeping in nonionic microemulsion electrokinetic chromatography with direct ultraviolet detection.
abstract: To separate and detect neutral solutes in nonionic microemulsion electrokinetic chromatography (MEEKC), a novel method was developed, combining complex formation and acetonitrile (ACN) sweeping. In this report, dynamic borate complexation and on-line sweeping occurred simultaneously during a run. The operating parameters which affected the performance of analyte sweeping in nonionic MEEKC were examined in terms of borate complexation, ACN content, Brij-35 concentration and sample plug length. In addition, the validation of the method included tests of the limit of detection, reproducibility and sensitivity enhancement. 60-110-Fold of magnitude improvement in detection sensitivity for model compounds (ginsenoside Rf, ginsenoside Rb2, ginsenoside Re) using Brij-35 microemulsion was demonstrated. Furthermore, the method was applied to the determination of glucosides in the plant extract.
authors.affiliation: Key Laboratory of Modern Chinese Medicines, China Pharmaceutical University, Ministry of Education, Nanjing 210009, China. caojun91@163.com
authors.forename: Jun
authors.initials: J
authors.lastname: Cao
authors.forename: Ling
authors.initials: L
authors.lastname: Yi
authors.forename: Ping
authors.initials: P
authors.lastname: Li
authors.forename: Yan-Xu
authors.initials: YX
authors.lastname: Chang
mesh_terms: D000097:Acetonitriles / Q000737:chemistry*; D020374:Chromatography, Micellar Electrokinetic Capillary / Q000295:instrumentation* / Q000379:methods*; D005960:Glucosides / Q000737:chemistry / Q000302:isolation & purification*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D000097:Acetonitriles; D005960:Glucosides; C032159:acetonitrile