Analysis of channel-geometry effects on separation efficiency in rectangular-capillary electrochromatography columns.
A three-dimensional random walk model was developed to evaluate the impact of column geometry on separation efficiency in chromatography systems driven by electroosmotic flow. Contributions of injection plug length, cross-sectional area of channels, and aspect ratio of rectangular channels were examined in these simulation studies. Sample plug length had no impact on efficiency until it exceeded roughly 0.4% of the channel length. Plate height increased rapidly with increasing k' as expected, almost doubling in going from k'=0.25 to 0.35. Channel geometry also had a major effect on efficiency. Plate height increased sharply in rectangular channel columns until the channel aspect ratio reached 4-8. But the effect of channel depth was even more dramatic. Minimum plate height (Hmin) was roughly half that of the channel depth in ideal cases. Hmin in a 10x2 microm channel was at 1.6 mm s(-1). Rectangular channels comparable to those obtained by microfabrication are equivalent to packed column capillary electrochromatography columns in all cases.
Zhang
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Department of Chemistry, Purdue University, West Lafayette, IN 47907-1393, USA.
Regnier
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D000465:Algorithms; D020374:Chromatography, Micellar Electrokinetic Capillary / Q000592:standards*; D007700:Kinetics