Identification of nitrated polycyclic hydrocarbons in diesel particulate extracts by negative ion chemical ionization and tandem mass spectrometry.

Solid phase extraction is used to clean-up diesel particulate extracts for an identification of nitrated polycyclic hydrocarbons (nitro-PAHs). Thirty eight nitro-PAHs were identified both by electron impact mass spectrometry, by negative ion chemical ionization (NICI) under selected ion monitoring (SIM) conditions and by tandem mass spectrometry. A substantial increase in selectivity is achieved if tandem mass spectrometry is employed leading to an enhancement of the signal to noise ratio and to a more reliable compound assignement