A method for sequentially performing a synthesis, separation and screening of chemical entities, especially a combinatorial library, is described. The method utilises a bulk of a stationary phase (e.g. silica gel, aluminium oxide, cellulose, etc. for example arranged on a backing) for the performance of the synthesis, separation and screening. The technique described enables a rapid route from synthesis to the testing of chemical compounds. Screening can be performed without need for reaction work-up. Preferred screening methods are those used to determine the biological activity of the compounds.