Temperature effects on electrophoresis.

We present a model capturing the important contributors to the effects of temperature on the observable electrophoretic mobilities of small ions, and on solution conductivity and pH. Our temperature model includes relations for temperature-dependent viscosity, ionic strength corrections, degree of ionization (pK), and ion solvation effects on mobility. We incorporate thermophysical data for water viscosity, temperature-dependence of the Onsager-Fuoss model for finite ionic strength effects on mobility, temperature-dependence of the extended Debye-Huckel theory for correction of ionic activity, the Clarke-Glew approach and tabulated thermodynamic quantities of ionization reaction for acid dissociation constants as a function of temperature, and species-specific, empirically evaluated correction terms for temperature-dependence of Stokes' radii. We incorporated our model into a MATLAB-based simulation tool we named Simulation of Temperature Effects on ElectroPhoresis (STEEP). We validated our model using conductivity and pH measurements across a temperature variation of 25-70 °C for a set of electrolytes routinely used in electrophoresis. The model accurately captures electrolyte solution pH and conductivity, including important effects not captured by simple Walden-type relations.