Capillary Electrophoresis CE -Mass Spectrometry

In capillary electrochromatography (CEC) a liquid flow through a packed capillary is created by appHcation of an electric field. Several interfaces have been designed for coupHng to ESI-MS, and current appHcations have been reviewed [93, 94]. CEC is a good alternative for neutral analytes in combination with mass spectrometric detection, since no interferences with miceUular matrix can occur [95]. The combination with LC, resulting in an electrically and a pneumatically driven flow of solvent, has been called pressurised CEC. This combination offers new opportunities for the separation of complex mixtures. 

---

Colorimetry, capillary electrophoresis (CE), ° mass spectrometry (MS), gas chromatography (GC), high-performance liquid chromatography (HPLC), thin-layer chromatography coupled with different detectors, and spectral techniques are the most commonly employed methods for trace environmental analysis of pesticides and also are part of regulations in monitoring the environmental pollutants. 

CE/MS. capillary electrophoresis and mass spectrometry used as a combined technique... 

SEQUENCING MHC CLASS I PEPTIDES USING MEMBRANE PRECONCENTRATION-CAPILLARY ELECTROPHORESIS TANDEM MASS SPECTROMETRY (mPC-CE-MS/MS)... 

In recent years, the coupling of capillary electrophoresis to mass spectrometry (CE-MS) has moved at an extraordinary pace, expanding out of the realm of a few and simple analytical chemistry applications into the development... 

Capillary electrophoresis and mass spectrometry can be coupled using a special ESI interface that provides an additional makeup flow, comprised of water, organic solvent, and acid, to create suitable conditions for ESI (Figure 2.14). Flow rates and sample loading are very low in CE. The supplemental sheath makeup liquid, while useful in the ESI process, has the effect of diluting the analyte, thereby compounding the sensitivity problem caused by the small amounts of analyte used in CE. The importance of CE is that the very large number of theoretical plates available enable complex separations that can reveal subtle differences in analytes. 

Identification of stmctures of toxic chemicals in environmental samples requires to use modern analytical methods, such as gas chromatography (GC) with element selective detectors (NPD, FPD, AED), capillary electrophoresis (CE) for screening purposes, gas chromatography/mass-spectrometry (GC/MS), gas chromatography / Fourier transform infra red spectrometry (GC/FTIR), nucleai magnetic resonance (NMR), etc. 

Over the past two decades, capillary electrophoresis (CE) and related techniques have rapidly developed for the separation of a wide range of analytes, ranging from large protein molecules to small inorganic ions. Gas chromatography has been considered as a powerful tool due to its sensitivity and selectivity, especially when coupled with mass spectrometry. Nevertheless, liquid chromatography is the most used method to separate and analyze phenolic compounds in plant and tissue samples. 

Capillary electrochromatography-mass spectrometry (CE-MS), 4 641 Capillary electrodes, 14 27 Capillary electrophoresis (CE), 4 602-603, 631-633 6 385 9 751-752 antibody based columns with, 6 402 chiral additives, 6 77-79 applications, 4 641 basic principles, 4 606-609 detectors, 4 634-635 for DNA analysis, 4 636-637 flow profiles generated, 4 608 instrumentation, 4 633 as microfluidic assay technique,... 

Other commonly used techniques include capillary electrophoresis (CE) and mass spectrometry. These techniques are discussed in other chapters in this book. 

Electrospray (ESI) is an atmospheric pressure ionization source in which the sample is ionized at an ambient pressure and then transferred into the MS. It was first developed by John Fenn in the late 1980s [1] and rapidly became one of the most widely used ionization techniques in mass spectrometry due to its high sensitivity and versatility. It is a soft ionization technique for analytes present in solution therefore, it can easily be coupled with separation methods such as LC and capillary electrophoresis (CE). The development of ESI has a wide field of applications, from small polar molecules to high molecular weight compounds such as protein and nucleotides. In 2002, the Nobel Prize was awarded to John Fenn following his studies on electrospray, for the development of soft desorption ionization methods for mass spectrometric analyses of biological macromolecules. ... 

II) complexes. This method was also successfully applied to chemically derivatized GAGs that cannot be depolymerized by enzymes [62]. Similarly, capillary electrophoresis (CE) can be used for digested GAGs that are then detected by ultraviolet spectroscopy or mass spectrometry. Complexation of GAGs using copper (II) ions improved the sensitivity. However, complete separation of intact GAGs was not feasible by CE and most methods still rely on enzymatic or chemical depolymerization prior to analysis [46]. 

Traditional biochemical techniques such as liquid chromatography (LC), gel electrophoresis, capillary electrophoresis (CE), and mass spectrometry (MS) have been widely used for the complete analysis of salivary proteins and peptides. The recent advances in these technical approaches applied to peptidomics have allowed a better comprehensive analysis of peptides in human whole saliva, envisioning the identification of potential salivary biomarkers of oral and systemic diseases. Sample preparation is a critical experimental step for the successful identification of peptides using MS-based approaches, for their quantitation and identification of PTMs. 

As an instrumental approach to conventional electrophoresis, capillary electrophoresis offers the capability of on-line detection, micropreparative operation and automation (6,8,45-47). In addition, the in tandem connection of capillary electrophoresis to other spectroscopy techniques, such as mass spectrometry, provides high information content on many components of the simple or complex peptide under study. For example, it has been possible to separate and characterize various dynorphins by capillary electrophoresis-mass spectrometry (33). Therefore, the combination of CE-mass spectrometry (CE-MS) provides a valuable analytical tool useful for the fast identification and structural characterization of peptides. Recently, it has been demonstrated that the use of atmospheric pressure ionization using Ion Spray Liquid Chromatography/ Mass Spectrometry is well suited for CE/MS (48). This approach to CE/MS provides a very effective and straightforward method which allow the feasibility of obtaining CE/MS data for peptides from actual biological extracts, i.e., analysis of neuropeptides from equine cerebral spinal fluid (33). 

---