The thermodynamic partitioning behavior of solutes into immobilized artificial membrane(IAM) and n-octanol/water systems was investigated, including acidic,basic,and amphoteric substances.In an n-octanol/buffer system,partitioning process was entropy-dominated for the most studied drugs,while partitioning of oxolinic and nalidixic acids into n-octanol phase was enthalpy-driven.In IAM chromatography,partitioning into membrane for the studied solutes was enthalpy-driven and an exothermal process.In conclusion,there is a significant difference of solutes′ partitioning mechanism into either IAM or an n-octanol phase,therefore,presenting the theoretical basis for differing lipophilicity measuring scale.
