A purification column is provided in which fluid is purified by flow through a purifying component. The column includes an annular wall defining a bore which, in use, contains the purifying component. The column further includes an inlet port to the bore comprising a first aperture through the annular wall, the inlet port being adjacent one end of the column. The column further includes an outlet port from the bore comprising a second aperture through the annular wall, the outlet port being adjacent the same end of the column as the inlet port. The column further includes a flow guidance device within the bore and removably connected to the inlet and outlet ports for guiding the fluid to the purifying component from the inlet port and for guiding the fluid from the purifying component to the outlet port. The flow guidance device maintains separation of the fluid flows to and from the purifying component.