Separation and identification of polynuclear aromatic compounds in coal tar by using glass capillary chromatography including combined gas chromatography-mass spectrometry

Abstract

Glass capillary chromatography combined with mass spectrometry has been used for the qualitative analysis of high-temperature coal tar. A simple method for making thermally stable wall-coated open tubular (WCOT) columns coated with the stationary phase SE-54 is described. More than 140 components with boiling points up to 870°K could be separated and identified or characterized. A typical pattern for polynuclear aromatics (PNAs) was found on columns having polarities ranging from the polar polyphenyl ether sulphone Poly S 179 to the less polar silicone liquids OV-61, OV-7 and SE-54. Comparison of the retention times of more than 40 standard compounds contained in a single test mixture enabled most of the major constituents to be assigned. A number of compounds that had not hitherto been reported to be constituents of coal tar were characterized by their mass spectra. These included two unknown compounds in the benzpyrene fraction. Coal tar may now serve as an inexpensive but very complete mixture for the gas chromatographic analysis of PNAs, because the retentions and/or orders of elution of a large variety of PNAs obtained on WCOT columns coated with various stationary liquids of different polarity have now been established.