Cylindrical peptide synthesis vessel with a 2 mm PTFE top valve, a GL-18 threaded side port and a removable fritted disc incorporated in the lower valve assembly. The coarse fritted disc is easily removed from the PTFE adapter for cleaning and / or replacement; dead space below the frit is eliminated by this design. Breakage of glass stopcock arms is also eliminated by the PTFE construction of the stems and the valve only requires a 1/4-turn from fully closed to fully open. The valve stem has 1/4-28 threads on the ID and the OD is sized for 3/8" compression fittings. All wetted surfaces are PTFE or borosilicate glass.