Capillary Electrophoresis CE

Capillary electrophoresis is based on the same principle as gel electrophoresis. Charged analytes can be separated in an applied electric field according to their mobility. In contrast to gel electrophoresis, however, separations are carried out in a small diameter capillary containing a free solution of electrolyte rather than on a slab gel. Moreover, convective flows due to Joule heating occur more easily in a free solution than in the gel. In contrast to GE, electroosmotic flow is often part of the separation process. 

Capillary electrophoresis has a wide applicability. High molecular weight compounds such as proteins, nucleic acids and oligosaccharides can be separated as well as smaller biomolecules such as peptides and amino acids. CE is not restricted to charged analytes. Neutral molecules can be separated from each other by employing a variation of CE called micellar electrokinetic chromatography (MEKC). This is frequently used for the separation of chiral drugs in pharmaceutical research. 

Capillary electrophoresis was developed in the 1980s by James Jorgenson and Krynn Lukas. They separated derivatised amino acids in a 75 tim inner diameter 

Capillary Zone Electrophoresis CZE charge and size ions 

Capillary Isoelectric Focussing CIEF isoelectric point, pi zwitter-ions 

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Capillary Electrophoresis. Capillary electrophoresis (ce) or capillary 2one electrophoresis (c2e), a relatively recent addition to the arsenal of analytical techniques (20,21), has also been demonstrated as a powerful chiral separation method. Its high resolution capabiUty and lower sample loading relative to hplc makes it ideal for the separation of minute amounts of components in complex biological mixtures (22,23). 

Capillary Electrophoresis. Capillary electrophoresis (ce) is an analytical technique that can achieve rapid high resolution separation of water-soluble components present in small sample volumes. The separations are generally based on the principle of electrically driven ions in solution. Selectivity can be varied by the alteration of pH, ionic strength, electrolyte composition, or by incorporation of additives. Typical examples of additives include organic solvents, surfactants (qv), and complexation agents (see Chelating agents). 

DEVELOPMENT OF INFRARED DETECTION IN FLOW INJECTION ANALYSIS (FIA) AND CAPILLARY ELECTROPHORESIS (CE)... 

One of the important problems in the diagnosis of different disease in their early stages is the determination of bio-active substances in biological fluids. We are currently interested in applying capillary electrophoresis (CE) as technique for the rapid and highly efficient separation of corticosteroids in semm and urine. Steroids can analyze by MEKC. 

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. 

Enantioresolution in capillary electrophoresis (CE) is typically achieved with the help of chiral additives dissolved in the background electrolyte. A number of low as well as high molecular weight compounds such as proteins, antibiotics, crown ethers, and cyclodextrins have already been tested and optimized. Since the mechanism of retention and resolution remains ambiguous, the selection of an additive best suited for the specific separation relies on the one-at-a-time testing of each individual compound, a tedious process at best. Obviously, the use of a mixed library of chiral additives combined with an efficient deconvolution strategy has the potential to accelerate this selection. 

Chiral additives have been shown to be very effective for chiral separations by capillary electrophoresis (CE) [4, 5]. Indeed, it may be argued that there has been considerably more research activity in chiral separations by CE than by EC methods since the introduction of the former technique. Chiral additives in CE have several advantages, some of which are highlighted in Table 11-2. 

Capillary electrophoresis (CE) has several unique advantages compared to HPLC, snch as higher efficiency dne to non-parabolic fronting, shorter analytical time, prodnction of no or much smaller amounts of organic solvents, and lower cost for capillary zone electrophoresis (CZE) and fused-silica capillary techniques. However, in CZE, the most popular separation mode for CE, the analytes are separated on the basis of differences in charge and molecular sizes, and therefore neutral compounds snch as carotenoids do not migrate and all co-elute with the electro-osmotic flow. 

Carmine extracted from cochineal insects is one of the most used natural colorings for beverages and other foods. Some representative articles refer to isolation and spectrometric analysis or the use of HPLC or capillary electrophoresis (CE) to separate and characterize all cochineal pigments. Its active ingredient, carminic acid, was quantified by rapid HPLC-DAD or fluorescence spectrometry. Carminic acid, used as an additive in milk beverages, was separated within 9 min using a high-efficiency CE separation at pH 10.0 after a previous polyamide column solid phase extraction (SPE), ... 

In addition to chromatography based on adsorption, ion pair chromatography (IP-HPLC) and capillary electrophoresis (CE) or capillary zone electrophoresis (CZE) are new methods that became popular and are sufficiently accurate for these types of investigations. Other methods involving electrochemical responses include differential pulse polarography, adsorptive and derived voltammetry, and more recently, electrochemical sensors. 

At present, the most promising methods for synthetic colorant analysis seem to be those based on separation approaches such as HPLC and capillary electrophoresis (CE). CE is the method of choice for the determination of synthetic dyes in biological materials while HPLC is generally a more suitable method for the identification and determination of hydrophobic natural pigments, having a better sensitivity and efficiency than CE. 

Sulfonylureas are not directly amenable to gas chromatography (GC) because of their extremely low volatility and thermal instability. GC has been used in conjunction with diazomethane derivatization, pentafluorobenzyl bromide derivatization, and hydrolysis followed by analysis of the aryl sulfonamides. These approaches have not become widely accepted, owing to poor performance for the entire family of sulfonylureas. Capillary electrophoresis (CE) has been evaluated for water analysis and soil analysis. The low injection volumes required in CE may not yield the required sensitivity for certain applications. Enzyme immunoassay has been reported for chlorsulfuron and triasulfuron, with a limit of detection (LOD) ranging from 20 to 100 ng kg (ppt) in soil and water. 

Capillary electrophoresis (CE) or capillary zone electrophoresis (CZE) is the technique most often employed in pesticide residue analysis. In its most basic form, free zone electrophoresis, a fused-silica capillary is filled with electrolyte (running buffer or background electrolyte). A potential is applied across the capillary and the cations... 

A number of developments have increased the importance of capillary electrophoretic methods relative to pumped column methods in analysis. Interactions of analytes with the capillary wall are better understood, inspiring the development of means to minimize wall effects. Capillary electrophoresis (CE) has been standardized to the point of being useful as a routine technique. Incremental improvements in column coating techniques, buffer preparation, and injection techniques, combined with substantive advances in miniaturization and detection have potentiated rugged operation and high capacity massive parallelism in analysis. 

Microwave plasma detection has been reviewed [351], also in relation to GC [352,353], Coupling of chromatography (GC, SFC, HPLC) and capillary electrophoresis (CE) with ICP-MS and MIP-MS detectors has also been reviewed [181,334,335]. Various specific GC-ICP-MS reviews have appeared [334,337,345,346,354,355]. 

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