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 chemi cal nature of adsorbates on aerosol particles which were collected fro m different sites, e.g. in the countryside, in an industrial zone, by a downtown road, and in a tunnel. The method combines infrared laser d esorption from the particle surfaces followed by ultraviolet laser pos t-ionization of the desorbed neutral molecules. Because of the high se nsitivity and optical selectivity of L2MS, virtually no sample prepara tion is needed, and mass spectra can be recorded in a very short time. Qualitative and quantitative comparisons of polycyclic aromatic hydro carbons in different sampling areas were carried out. By scanning the ionization laser wavelength, two-dimensional UV/MS spectra can be gene rated for better identification of the adsorbed species.