Temperature Dependence of Distribution Coefficients of Caffeine and Vanillin of Hydrophobic Resin in an Aqueous System

Abstract

The retention behaviors of caffeine and vanillin in columns packed with thermostable octadecyl silica gels and zirconium particles with an extremely stable thin layer of cross-linked polybutadiene were observed using water at various temperatures or methanol mixed with water at 30°C as the eluent. For both columns, the retention times of the solutes at a specific flow rate became shorter at higher temperatures when water was used as the eluent. The effect of the temperature on the retention behaviors of the solutes were examined for the latter column in the temperature range of 70°C to 210°C. It was shown that the retention behaviors could be more effectively controlled by changing the temperature when using water as the eluent than by changing the methanol content in its mixture with water at 30°C.