title: Isoelectric focusing in continuously tapered fused silica capillary prepared by etching with supercritical water.
abstract: This communication indicates the potential of etching with sub- and/or supercritical water for reproducible preparation of fused-silica capillaries with tapered geometry suitable for capillary isoelectric focusing (CIEF) with electroosmotic displacement. The etching procedure provided a single-piece combination of the tapered separation space with a cylindrical connection of the detection window to the electrode vial. Selected proteins and colored pI markers were used as model analytes. A comparison with conventional cylindrical capillary under comparable applied voltage and analysis time was made, and the resultant peaks were compared in terms of peak resolution under optimized conditions. In CIEF carried out in a tapered capillary with the inlet cross-section three times larger than the cross-section at the detection window, three to four times higher resolutions of corresponding peak pairs were obtained. The method described opens the way to increase the number of separable compounds without resorting to excessively high voltage.
authors.affiliation: Institute of Analytical Chemistry of the ASCR, v v i, Brno, Czech Republic. slais@iach.cz
authors.forename: Karel
authors.initials: K
authors.lastname: Slais
authors.forename: Marie
authors.initials: M
authors.lastname: Horká
authors.forename: Pavel
authors.initials: P
authors.lastname: Karásek
authors.forename: Josef
authors.initials: J
authors.lastname: Planeta
authors.forename: Michal
authors.initials: M
authors.lastname: Roth
mesh_terms: D000418:Albumins / Q000032:analysis; D007525:Isoelectric Focusing; D012822:Silicon Dioxide / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D000418:Albumins; D014867:Water; D012822:Silicon Dioxide