Membrane-related events can be investigated when the fluorescence of an intramembrane fluorophore is quenched by molecules that are dissolved in lipid phase. In this case the bimolecular quenching constant characterises the relative transport rate of the fluorophore and quencher molecules in the membrane interior and thereby it is related to the dynamics or structure of the membrane. Unlike classic quenching experiments, the crucial point in such studies is that the concentration of the quencher in the lipid phase differs from that in the bulk. As a consequence, it is usually described by different models, or regarded as the total concentration added. Here a simple fluorometric study is presented for distinguishing between the solvation mechanisms (partition or binding) of quencher molecules in membrane phase.