A RENEWABLE LIQUID DROPLET METHOD FOR ONLINE POLLUTION ANALYSIS BY MULTIPHOTON IONIZATION

A multi-photon ionization based fast conductance (MPIFC) technique was applied to detect combustion byproduct aerosols. These PAH-polluted a erosols were on-line sampled by means of renewable water microdroplets . The environmental cases considered here have involved such common ai r contaminants as motor car exhaust gas and cigarette smoke. The possi bility of obtaining useful calibration curves has been addressed. Two droplet contamination regimes were clearly observed. These have been a rgued to be associated with either a volume uniform (i.e., a bulk type ) or a surface-favored contamination. The latter regime is possible wh enever the increasing droplet contamination extends beyond the solubil ity saturation of the PAH compounds. Detection limits as low as 1 pg w ere obtained for pyrene-contaminated renewable microdroplets.