title: On-line concentration of neutral and charged species in capillary electrochromatography with a methacrylate-based monolithic stationary phase.
abstract: A method involving self-concentration, on-column enrichment and field-amplified sample stacking for on-line concentration in capillary electrochromatography with a polymer monolithic column is presented. Since monolithic columns eliminate the frit fabrication and the problems associated with frits, the experimental conditions could be more flexibly adjusted to obtain higher concentration factor in comparison with conventional particulate packed columns. With self-concentration effect, the detection sensitivity of benzene and hexylbenzene is improved by a factor of 4 and 8, respectively. With on-column enrichment and ultralong injection, improvement as high as 22,000 times in detection sensitivity of benzoin is achieved. Furthermore, a combination of the three above-mentioned methods yields up to a 24,000-fold improvement in detection sensitivity for caffeine, a charged compound. Parameters affecting the efficiency of on-line concentration are investigated systematically. In addition, equations describing on-line concentration process are deduced.
authors.affiliation: National Chromatographic Research and Analysis Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China.
authors.forename: Guichen
authors.initials: G
authors.lastname: Ping
authors.forename: Yukui
authors.initials: Y
authors.lastname: Zhang
authors.forename: Weibing
authors.initials: W
authors.lastname: Zhang
authors.forename: Lin
authors.initials: L
authors.lastname: Zhang
authors.forename: Lihua
authors.initials: L
authors.lastname: Zhang
authors.forename: Philippe
authors.initials: P
authors.lastname: Schmitt-Kopplin
authors.forename: Antonius
authors.initials: A
authors.lastname: Kettrup
mesh_terms: D001554:Benzene / Q000032:analysis; D001573:Benzoin / Q000032:analysis; D002110:Caffeine / Q000032:analysis; D002845:Chromatography / Q000295:instrumentation / Q000379:methods / Q000592:standards; D019075:Electrophoresis, Capillary / Q000295:instrumentation / Q000379:methods* / Q000592:standards*; D004867:Equipment Design; D008689:Methacrylates
chemical_list: D008689:Methacrylates; D002110:Caffeine; D001554:Benzene; D001573:Benzoin