ガスクロマトグラフによるアセトアルデヒド及び低級含酸素化合物の選択的検出

抄録

For the measurement of gaseous compounds in air, a selective detection method(O-FID) for oxygen-containing compounds was developed. Two methods were examined: a catalytic dehydrogenation-methanation method {O-FID (CDM)}and a direct catalytic methanation method {O-FID(DCM)}. The O-FID(CDM) was based on (1) the catalytic decomposition of oxygen-containing compounds to CO and CO₂ on reduced copper, (2) the conversion of CO and CO₂ to methane in a stream of hydrogen on nickel and (3) the detection with FID. The O-FID(DCM) made use of (1) the direct catalytic formation of methane on reduced copper with a flow of hydrogen and (2) the measurement of methane with FID. In both cases, hydrocarbons were removed adsorptively with active carbon. Gas chromatography was carried out with Shimadzu GC-4BM equipped with Porapak Q packed glass cloumn(i. d. 3 mm, 2 m long) at 130°C isothermally. By O-FID (CDM), almost all oxygen-containing compounds studied were measured and their sensitivities were similar to those of the usual FID, while those of hydrocarbons by O-FID(CDM) dropped to 1/1000 to 1/10000 and about 200μg of hydrocarbons did not cause any interferences for gas chromatographic measurement of oxygen-containing compounds at sub-μg levels. As the results, it was found that O-FID(CDM) could be used for the selective analysis of most oxygen-containing compounds. On the other hand, the O-FID(DCM) was more specific to acetaldehyde and ethanol among low oxygen-containing compounds examined. The sensitivity of the O-FID(DCM) was almost the same as the usual FID for acetaldehyde which was quantitized down to 2 ng under the gas chromatographic conditions mentioned above without any interferences from hydrocarbons.