APPLICATION OF 2-STEP LASER MASS-SPECTROMETRY TO THE CHEMICAL-ANALYSIS OF AEROSOL-PARTICLE SURFACES

Two-step laser mass spectrometry (L2MS) was applied to study the chemical nature of adsorbates on aerosol particles which were collected from different sites, e.g. in the countryside, in an industrial zone, by a downtown road, and in a tunnel. The method combines infrared laser desorption from the particle surfaces followed by ultraviolet laser post-ionization of the desorbed neutral molecules. Because of the high sensitivity and optical selectivity of L2MS, virtually no sample preparation is needed, and mass spectra can be recorded in a very short time. Qualitative and quantitative comparisons of polycyclic aromatic hydrocarbons in different sampling areas were carried out. By scanning the ionization laser wavelength, two-dimensional UV/MS spectra can be generated for better identification of the adsorbed species.