Development of a Time of Flight Mass Spectrometry Method for the Screening ofPolycyclic Aromatic Hydrocarbons and Nitro-Substituted Polycyclic Aromatic Hydrocarbons

摘要

Laser Desorption Ionization Time of Flight Mass Spectrometry LDI/TOFMS has beendeveloped for the direct screening of polycyclic aromatic hydrocarbons (PAHs) and nitrosubstituted polycyclic aromatic hydrocarbons (nitro-PAHs). An ultraviolet 266-nm laser desorbs and ionizes PAHs and nitro-PAHs from the filter support material. The ions are mass analyzed in a custom built time of flight mass spectrometer. The laser power dependence of ionization and fragmentation of positive ions for the PAH compounds listed in ARB method 429 has been examined. The negative ion yield of nitro-PAH that was targeted by the MLD source test method has also been systematically examined for fragmentation and ionization efficiency. The fragmentation/ionization studies show that there is a range of power densities that can produce molecular ion without significant fragmentation of the parent molecule for all but three of the compounds listed in Method 429. Naphthalene, acenaphthalene and acenapthene have relatively high vapor pressures.