What Ever Happened to Capillary Electrochromatography? - - Chromatography Online
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What Ever Happened to Capillary Electrochromatography?
Dec 1, 2009
By: Frantisek Svec, Ronald E. Majors
LCGC North America

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Ronald E. Majors
Over a decade ago, a new separation technique arose that was a variant of high performance liquid chromatography (HPLC) in which an electric field rather than an applied pressure drove the flow of mobile phase. The driving force was electroosmotic flow (EOF) and years before, in 1974, Victor Pretorius and coworkers (1) predicted that if EOF was used as a driving force for mobile phase flow rather than hydrodynamic flow, the efficiency of separations could be enhanced due to the flat band profile longitudinally across a column. The work of Jorgensen and Lukacs (2) in the early 1980s made use of EOF in open tubular capillaries and demonstrated low reduced plate heights. Although more attention was devoted to the development of capillary electrophoresis (CE) through the next decade, by the late 1990s, the principles of capillary electrochromatography (CEC) in packed capillaries had been demonstrated and this method was generating a great deal of attention. Any separation science conference or separation science session at major analytical instrument shows usually had standing room only and often, people were straining to get a view of the presentations in the hallway outside of the lecture room. Clearly, this was an exciting time, for researchers had predicted that CEC would have the selectivity of HPLC due to the presence of the stationary phase and have the efficiency of CE due to its high plate counts. There was even a belief that CEC could replace both HPLC and CE.


Figure 1
Today, one barely hears of CEC. At this year's HPLC 2009 meeting in Dresden, Germany, out of nearly 770 oral and poster papers, under 2% of the papers (one oral and 12 posters) addressed this topic, mostly around application examples. Crowds no longer strain to get a glimpse of a capillary electrochromatogram. How could this all come about after the extreme interest only ten years ago?


Figure 2
Still today, CEC has a following. Figure 1 shows the number of CEC papers published in the last decade and a half. Although the pace has somewhat slowed down, there has been an average of around 150 papers per year; that means that scientists are still investigating the parameters and developing applications despite the lack of commercial support. If one adds to it the number of patents involving CEC (Figure 2), there is a definite interest in the development of novel technologies around this field. So, again why isn't CEC gaining a foothold?

Earlier this year, at the 33rd International Symposium on Capillary Chromatography (ISCC) in Portland, Oregon, the subject of the apparent demise of CEC was the topic of a lively discussion session led by one of the authors of this text (FS). Some of the reasons why CEC has not come into favor were discussed among the many capillary experts in the audience as well as practitioners, many of whom never took up the technique. The same difficulties experienced with CEC that were brought up years ago were restated, but there was no general consensus on the main reasons for the low interest in CEC today.

In this installment of "Column Watch," using the ISCC discussion session as a starting point, we will explore the present state of the technology, speculating on reasons why the technique has not yet caught on, and present some arguments on why researchers should not give up on further investigations of the challenges that face CEC. We will also rely upon expert opinions that took place in a survey article in 1998 to see if any of their predictions came to pass (3).

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Source: LCGC North America, 12/1/2009
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