title: Ionization techniques in capillary electrophoresis-mass spectrometry: principles, design, and application.
abstract: A major step forward in the development and application of capillary electrophoresis (CE) was its coupling to ESI-MS, first reported in 1987. More than two decades later, ESI has remained the principal ionization technique in CE-MS, but a number of other ionization techniques have also been implemented. In this review the state-of-the-art in the employment of soft ionization techniques for CE-MS is presented. First the fundamentals and general challenges of hyphenating conventional CE and microchip electrophoresis with MS are outlined. After elaborating on the characteristics and role of ESI, emphasis is put on alternative ionization techniques including sonic spray ionization (SSI), thermospray ionization (TSI), atmospheric pressure chemical ionization (APCI), atmospheric pressure photoionization (APPI), matrix-assisted laser desorption ionization (MALDI) and continuous-flow fast atom bombardment (CF-FAB). The principle of each ionization technique is outlined and the experimental set-ups of the CE-MS couplings are described. The strengths and limitations of each ionization technique with respect to CE-MS are discussed and the applicability of the various systems is illustrated by a number of typical examples.
authors.affiliation: Department of Biomedical Analysis, Utrecht University, PO Box 80082, 3508 TB Utrecht, The Netherlands. p.hommerson@uu.nl
authors.forename: Paul
authors.initials: P
authors.lastname: Hommerson
authors.forename: Amjad M
authors.initials: AM
authors.lastname: Khan
authors.forename: Gerhardus J
authors.initials: GJ
authors.lastname: de Jong
authors.forename: Govert W
authors.initials: GW
authors.lastname: Somsen
mesh_terms: D019075:Electrophoresis, Capillary / Q000295:instrumentation / Q000379:methods; D004867:Equipment Design / Q000295:instrumentation* / Q000379:methods; D004364:Pharmaceutical Preparations / Q000032:analysis / Q000737:chemistry; D011506:Proteins / Q000032:analysis / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization / Q000295:instrumentation / Q000379:methods; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000295:instrumentation / Q000379:methods
chemical_list: D004364:Pharmaceutical Preparations; D011506:Proteins