Identification and differentiation of isomeric methylated derivatives of oxygenation products of polycyclic aromatic hydrocarbons by gas chromatography-mass spectrometry
An isomeric pair of compds. is obtained from 4-carboxyaldehydephenanthrene-5-carboxylic acid by various methods routinely applied for the methylation of acidic oxygenation products of K-region polycyclic arom. hydrocarbons (PAH's) prior to gas chromatog. and gas chromatog.-mass spectrometric anal. Differentiation of the individual cyclic and acyclic isomers, a classical general problem, proves possible by careful anal. of the mass spectral fragmentation patterns in the representative case studied here.