Selective retention of oxygen using chromatographic columns containing metal chelate polymers

Porous polymers containing various metal chelates bonded to nitrogen functionalities on the surface of the polymer have been synthesized and found to bind oxygen reversibly. The stationary phases containing [5,5'-(1,2-ethanediyldinitrilo)-bis(2,2,7-trimethyl-3-octanonato)]cobalt(II) were found to be the most suitable of the phases investigated for separating oxygen for argon, nitrogen, and carbon monoxide. At ambient temperatures, near 25 degrees C, the reversible interaction of molecular oxygen with the transition-metal complex bonded to the stationary phase results in a marked increase in the retention time of oxygen, relative to species that have similar retention times in columns that do not contain the metal chelate. The stationary phase can be used alone to achieve the separation of low molecular weight gases or in series with another column. The metal chelate stationary phase is selective for oxygen and little change in the retention time of oxygen is observed after hundreds of injections over a several-month period, indicating that no appreciable degradation of the stationary phase had taken place under these conditions.