Temperature profiles and heat dissipation in capillary electrophoresis

Area of Science:

• Analytical Chemistry
• Physical Chemistry

Background:

• Capillary electrophoresis (CE) typically uses external temperature control for precision.
• Internal electrolyte temperatures in CE are rarely measured, limiting accuracy and repeatability.
• Understanding temperature profiles is crucial for robust CE method development.

Purpose of the Study:

• To develop new equations for CE temperature profiles.
• To introduce a novel method for determining internal electrolyte temperatures.
• To investigate the impact of Joule heating on CE temperature.

Main Methods:

• Derived first-principles equations for mean, axial, and wall electrolyte temperatures.
• Utilized conductance (G) and electroosmotic mobility (μEOF) for temperature determination.
• Calibrated μEOF variation with temperature (T) by extrapolating μEOF vs. power per unit length (P/L) curves.

Main Results:

• Established relationships between mean, axial, and wall temperatures.
• Demonstrated that μEOF increases by 2.22%/°C.
• Experimentally determined temperatures using μEOF agreed within 0.2°C with G-based measurements.
• Found internal electrolyte temperatures up to 20°C higher than external temperatures under typical CE conditions.
• Quantified temperature differences across the capillary, coating, and stationary air layer.

Conclusions:

• Internal temperature measurement in CE is feasible and essential for accuracy.
• The developed method provides a complete temperature profile, including the stationary air layer.
• Accurate temperature profiling enhances the robustness and reliability of CE methods.