The invention provides an improved instrument for automation of solid phase extraction chemistries typically used in biotechnology labs. The instrument includes a mechanism for transferring samples dissolved in a liquid from initial containers to reaction columns that are used to perform solid phase extractions. Samples, reaction columns and collection containers are in microtiter plate format or tubes that are on 18 millimeter centers. The transfer system is automatically cleaned after use in preparation for the next use. A dispense manifold is used to dispense various reagents into the reaction columns. Pressure differential is used to move reagents through reaction columns. A sliding cover is used to divert the reagent exiting reaction columns to waste or allowing collection of sample as it exits outlets of reaction columns. Samples are automatically collected in microtiter plates or in individual tubes or vials.