Screening of aerosol filter samples for PAHs and nitro-PAHs by laser desorption ionization TOF mass spectrometry

Direct and selective screening of aerosol particulate matter for polycyclic aromatic hydrocarbons (PAHs) and nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) is achieved using laser desorption ionization time-of-flight (LDI TOF) mass spectrometry, Desorption and ionization of collected aerosol particulate matter was accomplished using pulsed UV radiation at 266 nm, P AHs were detected in positive ion spectra, while nitro-PAHs were selectivel y detected in negative ion spectra, Direct laser desorption ionization circ umvents extraction procedures necessary for HPLC or gas chromatography/mass spectrometry (GC/MS) analyses, and such screening offers potential cost sa ving by identifying samples which contain too little PAH for GC/MS analyses to be productive, Applicability of the LDI TOF method was demonstrated by collecting aerosol particles of less than 2.5 mu m aerodynamic diameter (PM 2.5) on Teflon filters from inside an urban bus terminal, Sampling of small air volumes (0.32-0.98 m(3)) was sufficient for LDI TOF analysis, Positive ion mass spectra of all collected aerosol samples exhibited peaks attribut ed to a wide range of PAHs, Of primary importance, selective ionization and detection of less abundant and more toxic nitro-PAHs is demonstrated in th e negative ion spectra, GC/MS analyses of duplicate filters confirmed laser desorption ionization analyses and assisted identification of specific PAH isomers.