DIFFERENTIATION OF ISOMERIC POLYCYCLIC AROMATICS USING NEGATIVE CHEMICAL IONIZATION.

Electron impact ionization mass spectrometry is of limited use in the unambiguous identification of isomeric polycyclic aromatic hydrocarbons (PAH). Negative chemical ionization (NCI) techniques have been investigated as a means of differentiating isomeric PAH without the use of standards. In a study of over thirty PAH, it was determined that a number of PAH may be distinguished on the basis of the EA values. A number of isomeric compounds may be distinguished using this technique, including two important benzopyrene isomers, benzo(a)pyrene, a potent carcinogen, and benzo(e)pyrene, which is not particularly carcinogenic.