Additives capillary electrophoresis

Juvancz, Z, 1 Urmos and 1 Klebovich (1996). Capillary electrophoretic separation of clomiphene isomers using various cyclodextrins as additives. Capillary Electrophoresis, 3(4), 181-189. 

Detectors Most of the detectors used in HPLC also find use in capillary electrophoresis. Among the more common detectors are those based on the absorption of UV/Vis radiation, fluorescence, conductivity, amperometry, and mass spectrometry. Whenever possible, detection is done on-column before the solutes elute from the capillary tube and additional band broadening occurs. 

Capillary Zone Electrophoresis The simplest form of capillary electrophoresis is capillary zone electrophoresis (CZE). In CZE the capillary tube is filled with a buffer solution and, after loading the sample, the ends of the capillary tube are placed in reservoirs containing additional buffer solution. Under normal conditions, the end of the capillary containing the sample is the anode, and solutes migrate toward... 

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). 

Library of Cyclic Oligopeptides as Additives to Background Electrolyte for Chiral Capillary Electrophoresis... 

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. 

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. 

Boyce, M.C., Determination of additives in food by capillary electrophoresis. Electrophoresis, 22, 1447, 2001. 

Tran, A. D., Park, S., Lisi, P. J., Huynh, O. T., Ryall, R. R., and Lane, P. A., Separation of carbohydrate-mediated microheterogeneity of recombinant human erythropoietin by free solution capillary electrophoresis. Effects of pH, buffer type and organic additives,. Ckromatogr., 542, 459, 1991. 

Peng, X., Bowser, M.T., Britz-McKibbin, P., Bebault, G.M., Morris, J.R., and Chen, D.D.Y., Quantitative description of analyte migration behavior based on dyamic complexation in capillary electrophoresis with one or more additives, Electrophoresis, 18, 706, 1997. 

Kang, J. and Ou, Q., Chiral separation of racemic mexilitine hydrochloride using cyclodextrins as chiral additive by capillary electrophoresis,. Chromatogr. A, 795, 394, 1998. 

Several additional instrumental techniques have also been developed for bacterial characterization. Capillary electrophoresis of bacteria, which requires little sample preparation,42 is possible because most bacteria act as colloidal particles in suspension and can be separated by their electrical charge. Capillary electrophoresis provides information that may be useful for identification. Flow cytometry also can be used to identify and separate individual cells in a mixture.11,42 Infrared spectroscopy has been used to characterize bacteria caught on transparent filters.113 Fourier-transform infrared (FTIR) spectroscopy, with linear discriminant analysis and artificial neural networks, has been adapted for identifying foodbome bacteria25,113 and pathogenic bacteria in the blood.5... 

Poli, J., Schure, M. Separation of Poly(styrenesulfonates) by capillary electrophoresis with polymer additives. Anal. Chem. 64, 896-904. 

Lin et al. [95] used capillary electrophoresis with dual cyclodextrin systems for the enantiomer separation of miconazole. A cyclodextrin-modified micellar capillary electrophoretic method was developed using mixture of /i-cyclodextrins and mono-3-0-phenylcarbamoyl-/j-cyclodextrin as chiral additives for the chiral separation of miconazole with the dual cyclodextrins systems. The enantiomers were resolved using a running buffer of 50 mmol/L borate pH 9.5 containing 15 mmol/L jS-cyclodextrin and 15 mmol/L mono-3-<9-phcnylcarbamoyl-/j-cyclodextrin containing 50 mmol/L sodium dodecyl sulfate and 1 mol/L urea. A study of the respective influence of the /i-cyclodcxtrin and the mono-3-(9-phenylcarbamoyl-/i-cyclodextrin concentration was performed to determine the optical conditions with respect to the resolution. Good repeatability of the method was obtained. 

A high performance capillary electrophoresis (HPCE) was described for the separation and simultaneous determination of OTC, TC, CTC, DC, and chloramphenicol in honey. The use of buffer pH 3.2 containing 0.02 mol/L Na2HP04 and 0.01 mol/L citric acid with addition of 4% (v/v) A-methylmorpholine and 12% (v/v) acetonitrile demonstrated a good separation of these five antibiotics within 20 min. The proposed method gave detection limit (signal to noise ratio > 5) of 20 pg/L for OTC [26],... 

Phinney et al. [Ill] investigated the application of citrus pectins, as chiral selectors, to enantiomer separations in capillary electrophoresis. Successful enantioreso-lution of primaquine and other antimalarials, was achieved by utilizing potassium polypectate as the chiral selector. Changes in pH, chiral additive concentration, and capillary type were studied in relation to chiral resolution. The effect of degree of esterification of pectin materials on chiral recognition was evaluated. 

Table 4.24 Some additives used in capillary electrophoresis ... 

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,... 

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