Capillary electrophoresis complexing agents

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). 

Pranfois, C., Morin, P., and Dreux, M. (1995). Separation of transition metal cations by capillary electrophoresis, optimization of complexing agent concentrations (lactic acid and 18-crown-6).. Chromatogr. A 717, 393—408. 

Dynamic sieving capillary electrophoresis (DSCE) employs a polymer solution as the sieving agent. It is introduced into the capillary under pressure and replenished after each analysis. The UV transparency of polymer solutions enables determination of native proteins. DSCE can be used for molecular weight determination of SDS-protein complexes because they migrate proportional to their molecular size. Polymer systems have been developed that provide good resolution of proteins in the 14-200 kDA range. 

Chiral separation in capillary electrophoresis is usually achieved by the addition of chiral complexing agents to form in situ diastereometric complexes between the enantiomers and the chiral complexing... 

In addition to these techniques, applications of capillary electrophoresis for lantharride analysis have appeared recently (Corr and Arracleto 1996, Vogt and Comadi 1994). Capillary electrophoretic separations rely on differences in the electrophoretic mobility of analyte species in an electrolyte buffer while tmder the influence of an applied electric field. For lanthanide analysis, the mobilities of the solvated cations are not adequately differentiated for an effective mutual separation, though separation from trarrsition metals or alkali/alkaline-earth metals should be readily accomplished. Introduction of chelating agents that form complexes with the ions leads to improved separation efficiency through... 

Track-etched polycarbonate filters and hydrophilic cellulose membrane filters (both 0.2 micron pore diameter, Whatman Filter Co.) were used to recover supernatant solutions. Total chelating agent and metal ion-chelating agent complex concentrations were determined using a Quanta 4000E capillary electrophoresis instrument (Waters Corp.) and bare fused-silica capillaries (75 microns wide, 60 cm long. Polymicro Technol.). The capillary electrolyte consisted of 25 mM phosphate buffer (pH 7.0) and 0.5 mM tetradecyl trimethylammonium bromide (TTAB) electroosmotic flow modifier (see (29)). 

There are more approaches to the analysis of chemical warfare agents than just the chromatographic or mass spec-trometric based techniques. These include nuclear magnetic resonance spectroscopy (NMR) or spectrophotometric detection. Additional approaches similar to GC, LC and MS are capillary electrophoresis (CE) and ion mobility spectroscopy (IMS). This chapter describes the instrumentation used to analyse and detect chemical warfare agents, from the simplest of techniques to the more complex, which allow for precise and accurate detection at very low levels. The authors have tried to be as comprehensive as possible in outlining the various methods utilized however, it is understood that because of the implications of GW As, there may be proprietary or classified methods, not yet in the public domain. 

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