| Abstract | Combined chromatog.-mass spectrometric studies, of the kinds outlined here, can be of great benefit in subdividing complex environmental or petroleum-derived mixts. of PAC into more manageable fractions. In the case of the environmental samples, which are extensively oxidized and contain mainly non-alkylated PAC, it is possible to achieve a moderate degree of chromatog. resoln. within ring isomer sets. The situation is more complicated in the extensively hydrogenated and alkylated crude oil samples, where the nos. of isomeric possibilities are too great for the approach taken to yield good sepn. Further work is needed on the fractionation of such samples. Each of the mass spectrometer interfaces used in this study has particular advantages: the moving belt permits the acquisition of true electron impact- or chem.-ionization mass spectra of compds. of mol. wt. approaching 1000 Da; the Heated Nebulizer Interface (HNI) can be used in combination with selective chem. ionization reagents to give an extremely sensitive detection system. It is expected that, with some development, the HNI will be useful for the chromatog.-mass spectrometric detn. of PAC of even higher mol. wt. |
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