Instrumentation electrochromatography

Recently a decreased level of CE activity has been noticed with a shift of attention towards other separation techniques such as electrochromatography. CE is apparently not more frequently used partly because of early instrumental problems associated with lower sensitivity, sample injection, and lack of precision and reliability compared with HPLC. CE has slumped in many application areas with relatively few accepted routine methods and few manufacturers in the market place. While the slow acceptance of electrokinetic separations in polymer analysis has been attributed to conservatism [905], it is more likely that as yet no unique information has been generated in this area or eventually only the same information has been gathered in a more efficient manner than by conventional means. The applications of CE have recently been reviewed [949,950] metal ion determination by CE was specifically addressed by Pacakova et al. [951]. 

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,... 

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... 

Capillary electrochromatography (CEC) is a rapidly emerging analytical separation technique, with several different instrumental formats and prepacked CEC capillary columns now available. P15-323 As an advanced nanoseparation technology, CEC represents an orthogonal hybrid of HPLC and HP-CZE. As a consequence, resolution can be achieved... 

Figure 26 Instrumentation Design for Pressurized Flow Electrochromatography of Peptides...

The fact that electrochromatography has overcome its typical "childhood problems" is proved by the steadily increasing number of applications, as confirmed in the last chapter of this book. Clearly, electrochromatography provides the analyst with a new tool which understandably, and as with many other instrumental analytical methods, is not generally applicable to all separation tasks. However, the number of difficult separations that has been achieved elegantly using CEC within recent years is, in our opinion, sufficient to justify publication of a monograph on this subject. 

The potential influence of the nature of the driving force on the chromatographic selectivity for neutral molecules has been investigated using CEC, pLC and pressurised flow electrochromatography. The comparison was performed on the same prototype instrument and the same column to eliminate all other possible influences... 

Electrochromatography and Mass Spectrometry Instrumental Aspects, Separation Systems, and... 

Flush for several hours at normal flow rates with the mobile phase to be used for the separation. Further condition on the capillary electrochromatography instrument with a stepwise increase in the operating voltage until a stable and adequate electroosmotic flow is obtained. 

Figure 8.14. Schematic diagram of a pneumatic system retrofitted to a capillary electrophoresis instrument for capillary electrochromatography with simultaneous pressurization of the column inlet and outlet reservoirs.

Packed colunms with sintered frits (section 8.4.2) are generally operated at an elevated pressure to minimize bubble formation by applying an equal pressure to the column inlet and outlet electrolyte solution reservoirs. Pressures less than 500 p.s.i. are adequate for this purpose. A suitable setup to adapt a capillary electrophoresis instrument for use in capillary electrochromatography with pressure-equalized column operation is shown in Figure 8.14 [262]. 

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