Fig. 1. Transfer free energies for (A ) chloroform and (B ) 1-chloro-1,2,2-trifluorocyclobutane between the gas and four solvent phases that model various microenvironments present in biologic membranes. Error bars are SD. The transfer free energies of the anesthetics between the gas and solvent phases were calculated as ΔG^g→^s=−RTln(C^s/C^g), where R is the gas constant (1.987 cal/mol K), T is the temperature in kelvins, and C^sand C^gare the solvent and gas phase concentrations of the anesthetic molecules at equilibrium.