TEMPERATURE ELEVATIONS OF THE SAMPLE ZONE IN FREE SOLUTION CAPILLARY ELECTROPHORESIS UNDER STACKING CONDITIONS

The combination of a low specific conductivity ratio of sample solution to surrounding running buffer (under stacking conditions) and high applied potentials can result in high power inductions and high temperatures of the sample zone. Eventually boiling occurs. Calculations of the sample zone and running buffer temperatures are based on changes in viscosity, relative permittivity, zeta potential and specific conductivity of the buffer solutions as a function of temperature. The temperature gradients across the capillary inner radius, the glass wall, the polyimide coating and the ''thermo layer'' from the capillary outer coating to the surroundings are estimated. Heat-transfer coefficients for liquid- and air-cooled capillaries were obtained.