Abstract:

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. 

Key words: Thermodynamic partitioning behavior; IAM chromatography; n-Octanol/water system; Membrane interactions