the purified resin substrate material were slurried in methanol and 6 26 grams of a 1m solution of dtbuch18c6 in 1 octanol were added the resulting mixture was gently stirred for several minutes and the methanol was removed under vacuum at 40 u00b0 c to yield about 16 g of the crown ether diluent dispersed on the resin substrate material to prepare the chromatographic column a portion of this resin substrate material was slurried in 3m nitric acid and aliquots of this slurry were transferred under nitrogen pressure to a 10 cm glass bio rad column 1 4 mm inside diameter equipped with polypropylene fittings manufactured under the trademark 34 cheminert 34 by chromatronix inc berkeley calif when the desired bed height had been reached corresponding to a bed volume of about 0 6 cm 3 the resin substrate material was resettled by backwashing the resin substrate material was then rinsed with several bed volumes of 3m nitric acid chromatographic columns can also be prepared in 23 cm long glass pasteur pipettes having a small glass wool plug in the bottom and a layer of 80 100 mesh glass beads on top of the resin substrate material to prevent disruption of the bed by sample introduction because these pipettes lack a.