Recent advances in capillary electrophoresis/electrospray/mass spectrometry

Abstract

Successful on-line interfacing of capillary electrophoresis (CE) with electrospray (ES) mass spectrometry (MS) has progressed substantially in recent years. Of particular note also is the development which has occurred in combining the more advanced capillary-based electromigration separation techniques, such as capillary gel electrophoresis (CGE), capillary isoelectric focusing (CIEF), capillary isotachophoresis (CIT), micellar electrokinetic chromatography (MEKC) and capillary electrochromatography (CEC), with ES/MS. The union of these electromigration schemes with MS detection provides a useful and sensitive analytical tool for the separation, quantitation and identification of biological, therapeutic, environmental and other important classes of chemical analytes. By making optimal use of the characteristics inherent with these separation mechanisms, greatly enhanced MS performance may be obtained. The following review summarizes the significant issues and challenges involved with CE/ES/MS analysis as well as results which have recently been obtained.

Coupling CE with atmospheric pressure photoionization MS for pharmaceutical basic compounds: Optimization of operating parameters

“…The limited sensitivity of CE when combined with UV detection is one of the major drawbacks regularly reported. However, other more sensitive detectors can be coupled with CE such as MS. Hyphenation of CE with MS combines the previously described advantages of CE with quasi-universality, high sensitivity as well as selectivity of MS [1][2][3][4]. Among ionization interfaces available, electrospray (ESI) is the predominant technique used for the on-line coupling of CE with MS as it is well suited for the analysis of polar compounds separated by CZE.…”

Capillary electrophoretic analysis of proteins and peptides of biomedical and pharmacological interest

“…Alternatively, peptides can be pre-or post-column derivatized with a number of fluorescent dyes, as reviewed in [56,57], among which: fluorescein isothiocyanate, fluorescamine and the near-infrared fluorescent dye NN382 [58] and the fluorogenic dye 5-furoyl-quinoline-3-carboxyaldehyde [59]. Mass spectrometry, in addition, represents perhaps the ultimate in peptide detection, since it couples good sensitivities (low femtomoles) to the ability of identifying the peptide via the possibility of obtaining its sequencing in the post-source decay mode in MALDI-TOF instrumentation [60,61]. There are plenty of examples of separations of peptides by CE, of which we will here recall a few (many more can be found in Reference [12]).…”

Method Development by Use of Capillary Electrophoresis and Applications in Pharmaceutical, Biological and Natural Samples

“…This was not a surprising observation since the sheath liquid plays an important role in the CE-MS system. The sheath liquid is used as the make-up liquid that can solve the flow-rate incompatibility problems between CE and MS [35]. These problems are encountered because the flow rate through the CE column is very low (nL/min), and it cannot support a stable electrospray, whose flow rate is typically a few μL/min.…”