A device for separating one or more molecules of interest in a liquid specimen including a monolithic body defining a fractionation column. The column includes an inlet opening at a proximal end of the fractionation column; an outlet opening at a distal, opposite end of the fractionation column; a solid phase chamber positioned between the inlet opening and the outlet opening; a specimen introduction area adjacent a proximal end of the solid phase chamber; an analyte exit area adjacent a distal end of the solid phase chamber; an inlet chamber adjacent the inlet opening that tapers into the specimen introduction area; and an outlet chamber that extends from the analyte exit area to the outlet opening. A metered amount of solid phase packed within the solid phase chamber between a first porous frit and a second porous frit of the solid phase chamber.