GAS-CHROMATOGRAPHIC DETERMINATION OF TRACE IMPURITIES IN HIGH-PURITY NITROGEN USING HYDROGEN STORAGE ALLOYS AS A NITROGEN ADSORBENT

A combination of two different hydrogen storage alloys was used to assist in the gas chromatographic determination of trace impurities, such as neon, argon, krypton, methane, and xenon, in nitrogen. This system consists of a gas chromatograph combined, in series, with two precolumns filled with TI/Mn-type and Ca-type hydrogen storage alloys. The former alloy efficiently retains nitrogen at 250-degrees-C and under the pressure of the carrier gas. The latter alloy is used in order to more efficiently adsorb hydrogen, which is released from the former alloy, at ambient temperature. By using a photoionization detector, the detection limits achieved were as follows: 3.7, 0.08, 0.03, 0.04, and 0.09 ppm for Ne, Ar, Kr, CH4, and Xe, respectively.