Abstract
A new gas chromatographic method for aldehydes analysis with their imidazolidine derivatives was developed. N, N'-diphenylethylenediamine easily reacts with aldehydes to form the imidazolidine derivative in the presence of acid catalyst. Differing from the peak of 2, 4-dinitrophenylhydrazone on a gas chromatogram, the peak corresponding to the imidazolidine derivative is single because of the absence of geometrical isomers. The gas chromatographic conditions were as follows : column packing, 1% PEG-HT on Chromosorb WAW DMCS; column size, 2 mm i.d. ×2.25 m or 3 m; detector, FID; column temp., (235265)°C (1°C/min); inj. port, 265°C; detector temp., 265°C. The imidazolidine derivatives of formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, iso-butyraldehyde, furfural, benzaldehyde and ο-tolualdehyde were clearly separated by the gas chromatographic conditions presented above. But, when acetaldehyde and butyraldehyde are mixed together, each aldehyde can't be identified because the retention time of both imidazolidine derivatives overlaps each other. In such a case, each aldehyde should be identified by using column packing of both 2% OV-17 and 1% PEG-HT. The relative mole response to anthracene as internal standard substance are as follows: the formaldehyde derivative, 0.85; the acetaldehyde derivative, 0.92; the propionaldehyde derivative, 1.18. The presented method was applied to analyse aldehydes in the cigarette smoke and the exhaust gas of automobiles, and several aldehydes were identified in both cases. The gas chromatographic method presented above can be used for analysis of aldehydes as their imidazolidine derivatives.
