depression 208 the closure plate 204 with the disk 242 secured in it is assembled as part of the apparatus set forth in fig5 in the previously described manner it should be noted that even though the disk 242 is made from a number of segments such as the segments 226 228 and 248 all of these segments are made from the same sintered stainless steel with substantially a 0 5 micron pore size the segmented composite disk such as the disk 242 can also contain more rings or less rings than those shown in fig7 and 8 with respect to the disk 242 the number will be chosen by those skilled in the art by the desired size for the disk along with other factors known in the art the composite segmented disk such as the disk 242 can be substituted for the previously described disks 60 188 and 218 in general the segmented composite type disk 242 or the like will be used for the larger size disks whereas the single piece non segmented disks 60 188 and 218 would be smaller in size the chromatography apparatus 10 and 202 are made and used in the following manner the cylinder 12 and its retainer collars 26 and 28 are made in the preferred embodiment from polycarbonate using suitable forming and machining techniques known in the art.