Determination of partition coefficient by the change of main phase transition

The molar partition coefficients of amphiphilic additives, e.g. local anest hetics, between the aqueous phase, the liquid crystal and the gel phase of lipid membrane can be determined based on a combination of phase transition data obtained at high and low concentrations of the lipid in aqueous phase . The data obtained at high lipid concentration allow to find the phase dia gram lipid-additive in the aqueous environment. The combination of this dia gram with data obtained at low lipid and additive concentrations provides d irect information on the concentration of anesthetics in the lipid and thus allows the calculation of the partition coefficient.