An aerosol mass
spectrometer for ultrafine aerosol particles was constructed. The operation of
the apparatus is based on the aerosol particle collection onto a metal surface
over a short period. The near real-time aerosol particle collection makes
possible an analysis of the particle phase compounds with short lifetimes. The
collected aerosol particles are charged with a bipolar charger, size-separated
by a differential mobility analyzer according to their electrical mobility and
collected via electrostatic deposition on the electrically charged metal surface
of a sampling valve. The collected particles are subjected to a two-step laser
desorption ionization before the mass spectrometric analysis. The ionized
molecules are analyzed according to their m / z ratios and detected
with a micro-channel plate detector. The aerosol mass spectrometer was
calibrated with different chemical compounds, and its applicability for the
determination of selected organic compounds was studied. The calibration of the
mass axis showed a good correlation ( R ² = 0.9996). Mass
spectral data for ultrafine ambient aerosol particles was obtained at
sub-picogram concentrations.