The principle of phase equilibrium is applied to the determination of desorption efficiencies of organic compounds collected on activated charcoal. The method depends on the existance of a true equilibrium distribution between the adsorbed and solution phases of organics in the desorption solvent--adsorbent matrix. Improved and more consistant desorption efficiencies are obtained by considering the effects of variations in the adsorbent--solvent ratio and equilibrium temperature at time of analysis. The technique may also provide early detection of interaction or reaction of the sorbate on the adsorbent surface.