Operating HPLC at higher than ambient temperatures can improve peak shapes and enable faster run times. Preheating the mobile phase is significant in high temperature liquid chromatography as the relationship between temperature and viscosity strongly influences the mobile phase flow profile and the diffusion characteristics. With temperature programming, thermal gradients mimic solvent gradients because of the changing polarity of the mobile phase and interactions with the stationary phase; often thermal gradients can replace solvent gradients.
