Abstract
A knowledge of the heat-transfer coefficient, h(s), for the external surface of the capillary or the overall heat coefficient, hop, is of great value in predicting the mean increase in temperature of the electrolyte, Delta T-Mean, during electrokinetic separations. A novel method for h(s) determination in CE is introduced, which is based on curve-fitting of plots of conductance versus voltage to calculate several important parameters including Delta T-Mean, the conductance free of Joule heating effects (G(0)) and the voltage that causes autothermal runaway, V-lim.
The new method is superior to previously published methods in that it can be performed more quickly and that it corrects for systematic errors in the measurement of electric current for voltages <5 kV. Axially averaged values for h(s) were determined for three different commercial CE instruments ranging from 164 W m(-2) K-1 for a passively cooled instrument in a drafty environment to 460 W m(-2) K-1 for a liquid-cooled instrument.