The study on solubilities of substances in dense gases is one of the most important tasks in supercritical fluid extraction(SFE).On the basis of the association laws and the adsorption theories,this paper puts forward a kind of physicochemical mechanism of SFE.Based on this mechanism an adsorption/association model for calculating solubilities of substances in a supercritical fluid(SCF)has been derived.Some experimental results from the literature were reproduced by means of this model.Very good agreement w...