Cations electrophoresis

Wang, J., G. Chen, A. Muck, Jr., and G. E. Collins. Electrophoretic microchip with dual-opposite injection for simultaneous measurements of anions and cations. Electrophoresis 24, 3728-3734 (2003). 

Buxbaum, E. (2003) Cationic electrophoresis and electrotransfer of membrane glycoproteins. Anal. Biochem. 314, 70-76. 

Capillary zone electrophoresis also can be accomplished without an electroosmotic flow by coating the capillary s walls with a nonionic reagent. In the absence of electroosmotic flow only cations migrate from the anode to the cathode. Anions elute into the source reservoir while neutral species remain stationary. 

Capillary zone electrophoresis provides effective separations of any charged species, including inorganic anions and cations, organic acids and amines, and large biomolecules such as proteins. For example, CZE has been used to separate a mixture of 36 inorganic and organic ions in less than 3 minutes.Neutral species, of course, cannot be separated. 

Electroosmotic flow in a capillary also makes it possible to analyze both cations and anions in the same sample. The only requirement is that the electroosmotic flow downstream is of a greater magnitude than electrophoresis of the oppositely charged ions upstream. Electro osmosis is the preferred method of generating flow in the capillary, because the variation in the flow profile occurs within a fraction of Kr from the wall (49). When electro osmosis is used for sample injection, differing amounts of analyte can be found between the sample in the capillary and the uninjected sample, because of different electrophoretic mobilities of analytes (50). Two other methods of generating flow are with gravity or with a pump. 

Modes of Operation There is a close analogy between sedimentation of particles or macromolecules in a gravitational field and their elec trophoretic movement in an electric field. Both types of separation have proved valuable not only for analysis of colloids but also for preparative work, at least in the laboratoiy. Electrophoresis is applicable also for separating mixtures of simple cations or anions in certain cases in which other separating methods are ineffectual. 

For example, Barlow and Margoliash [33] showed that phosphate, chloride, iodide, and sulfate, in decreasing order of effect, reduced the electrophoretic mobihty of human cytochrome c at pH 6.0 by up to a factor of 2. The cations lithium, sodium, potassium, and calcium had no effect. It is possible to account for the binding equilibria of these counterions so that the titration and electrophoresis results can be compared however, in many of the early electrophoresis experiments these data were not available and relevant conditions were not recorded or controlled. For general discussions on the extensive field of ligand binding to proteins, see Cantor and Schimmel [60] and van Holde [403]. 

Maaloum, M Pernodet, N Tinland, B, Agarose Gel Structure Using Atomic Force Microscopy Gel Concentration and Ionic Strength Effects, Electrophoresis 19, 1606, 1998. Mackie, IS Meares, P, The Diffusion of Electrolytes in a Cation-Exchange Resin Membrane I. Theortical, Proceedings of the Royal Society of London Series A 232, 498, 1955. 

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... 

Breadmore, M. C., Macka, M., and Haddad, P. R., Manipulation of separation selectivity for alkali metals and ammonium in ion-exchange capillary electrochromatography using a suspension of cation exchange particles in the electrolyte as a pseudo stationary phase, Electrophoresis, 20, 1987, 1999. 

Wiktorowicz, J. E. and Colburn, J. C., Separation of cationic proteins via charge reversal in capillary electrophoresis, Electrophoresis, 11, 769, 1990. 

Gassner, B., Friedl, W., and Kenndler, E., Wall adsorption of small anions in capillary zone electrophoresis induced by cationic trace constituents of the buffer, /. Ckromatogr., 680, 25, 1994. 

Beck, W. and Engelhardt, H., Capillary electrophoresis of organic and inorganic cations with indirect UV detection, Chromatographia, 33, 313, 1992. 

Weston, A., Brown, P. R., Jandik, P., Heckenberg, A. L., and Jones, W. R., Optimization of detection sensitivity in the analysis of inorganic cations by capillary ion electrophoresis using indirect photometric detection,. Chromatogr., 608, 395, 1992. 

The guanine radical cations (G +) are detected by their reactions with water, which leads after treatment with piperidine or ammonia to selective strand cleavage [14]. A similar charge detection method was used by J.K. Barton, G.B. Schuster and I. Saito as described in their articles in this volume. The cleavage products were separated and quantified by gel electrophoresis. A typical example is shown in Fig. 7 where the GGG unit acts as a thermodynamic sink for the positive charge, and the efficiency of the charge transfer can be measured by the product ratio Pggg/Pg-... 

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