Abstract
The relative velocity difference (ΔU/U av) of two zones, separated by capillary zone electrophoresis, increased with increasing buffer concentration, but remained constant for a given concentration regardless of electric field strength. For diffusionlimited band broadening, the increase in ΔU av offset a decrease in migration velocity to provide slightly better resolution. In practice, however, additional dispersion occurred as a result of Joule heating, especially when concentrated buffers, high electric field strengths and/or capillaries with large internal diameters were employed. To improve efficiency, under such conditions, forced air convection was investigated as a means for dissipating some of the Joule heat generated. In 100-μm capillaries, forced convection increased efficiency from 190 000 ± 3.1% relative standard deviation (R.S.D.) to 226 000 ± 3.3% R.S.D. theoretical plates. For comparison, 264 000 theoretical plates were observed in 50-μm capillaries under similar operating conditions. In the latter case the improved efficiency is, however, obtained at the expense of sample capacity.
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