Capillary electrochromatography stationary phases

Aptamers have an even more diverse role in diagnostics. - Highly specific aptamers have been used as affinity probes in CE and proteomic microarrays. " - Aptamers have been incorporated into fluorescent switches and beacons. - They have been incorporated into chromatography and capillary electrochromatography " stationary phases. They have even been used as the sensing element of cantilever-based detectors." Clearly, the combination of high affinity and selectivity provided by aptamers can be applied to a wide range of analytical techniques. 

Capillary Electrochromatography Another approach to separating neutral species is capillary electrochromatography (CEC). In this technique the capillary tubing is packed with 1.5-3-pm silica particles coated with a bonded, nonpolar stationary phase. Neutral species separate based on their ability to partition between the stationary phase and the buffer solution (which, due to electroosmotic flow, is the mobile phase). Separations are similar to the analogous HPLC separation, but without the need for high-pressure pumps, furthermore, efficiency in CEC is better than in HPLC, with shorter analysis times. 

Sander, L.C. et ah. Separation of carotenoid isomers by capillary electrochromatography with C30 stationary phases. Anal. Chem., 71, 3477, 1999. 

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. 

Zhang, M., Yang, C., and Ziad, E. R., Capillary electrochromatography with novel stationary phases. 3. Retention behavior of small and large nucleic acids on octadecyl-sulfonated-silica, Anal. Chem., 71, 3277, 1999. 

Hoegger, D.Freitag, R. (2001). Acrylamide-based monoliths as robust stationary phases for capillary electrochromatography. J. Chromatogr. A 914, 211-222. 

This overview concerns the new chromatographic method - capillary electrochromatography (CEC) - that is recently receiving remarkable attention. The principles of this method based on a combination of electroosmotic flow and analyte-stationary phase interactions, CEC instrumentation, capillary column technology, separation conditions, and examples of a variety of applications are discussed in detail. 

Keywords. Capillary electrochromatography, Theory, Electroosmotic flow, Separation, Instrumentation, Column technology, Stationary phase, Conditions, Applications... 

Molecular imprinting has recently attracted considerable attention as an approach to the preparation of polymers containing recognition sites with predetermined selectivity. The history and specifics of the imprinting technique pioneered by Wulff in the 1970s have been detailed in several excellent review articles [122-124]. Imprinted monoliths have also received attention as stationary phases for capillary electrochromatography. 

Capillary electrochromatography is based on the effect of interaction of the analyte with the stationary phase on its electrophoretic mobility. 

Fanah, S., Catarcini, P., and Presutti, C., Enantiomeric separation of acidic compounds of pharmaceutical interest by capillary electrochromatography employing glycopeptide antibiotic stationary phases, J. Chromatogr. A, 994, 227, 2003. 

Desiderio, C., Aturki, Z., and Eanali, S., Use of vancomycin silica stationary phase in packed capillary electrochromatography I. Enantiomer separation of basic compounds. Electrophoresis, 22, 535, 2001. 

Schmid, M.G, et al., Enantioseparation of dipeptides by capillary electrochromatography on a teicoplanin aglycone chiral stationary phase, J. Chromatogr. A., 990, 83, 2003. 

Mangelings, D., Hardies, N., Maftouh, M., Suteu, C., Massart, D.L., Vander Heyden, Y. Enantioseparations of basic and bifunctional compounds by capillary electrochromatography using polysaccharide stationary phases. Electrophoresis 2003, 24, 2567-2576. 

Vegvari, A., and Guttman, A. (2006). Theoretical and nomenclatural considerations of capillary electrochromatography with monolithic stationary phases. Electrophoresis 27, 716—725. 

Smith, N., and Evans, M. B. (1999). Comparison of the electroosmotic flow profiles and selectivity of stationary phases used in capillary electrochromatography.. Chromatogr. A 832, 41-54. 

Hilhorst, M. J., Somsen, G. W., and de Jong, G. J. (2000). Capillary electrochromatography of basic compounds using octadecyl-silica stationary phases with an amine-containing mobile phase. /. Chromatogr. A 872, 315—321. 

Capillary electrochromatography (CEC) is a miniaturized separation technique that combines aspects of both interactive chromatography and capillary electrophoresis. In this chapter, the theory of CEC and the factors affecting separation such as the stationary phase and mobile phase parameters have been discussed. The chapter focuses on the types and preparation of columns for CEC and describes the progress made in the development of open-tubular, particle-packed, and monolithic columns. The detection techniques in CEC such as the traditional UV detection and improvements made in coupling with more sensitive detectors such as mass spectrometry are also described. The chapter provides a summary of some applications of CEC in the analysis of pharmaceuticals and biotechnology products. 

McKeown, A. P., Euerby, M. R., Johnson, C. M., Koeberle, M., Lomax, H., Ritchie, H., and Ross, P. (2000). An evaluation of unbonded silica stationary phases for the separation of basic analytes using capillary electrochromatography. Chromatographia 52, 777-786. 

Zimina, T. M., Smith, R. M., and Myers, P. (1997). Comparison of ODS-modified silica gels as stationary phases for electrochromatography in packed capillaries. /. Chromatogr. A 758, 191-197. 

Dittmann, M. M., and Rozing, G. P. (1997). Capillary electrochromatography investigation of the influence of mobile phase and stationary phase properties on electroosmotic velocity, retention, and selectivity. J. Microcolumn Sep. 9, 399-408. 

Guihen, E., and Glennon, J. D. (2004). Recent highlights in stationary phase design for open-tubular capillary electrochromatography /. Chromatogr. A 1044, 67-81. 

Hindocha, D., and Smith, N. W. (2002). The analysis of basic pharmaceutical compounds by capillary electrochromatography using continuous bed stationary phase. Chromatographia 55, 203-209. 

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