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MASS SPECTROMETRY OF INDIVIDUAL AEROSOL PARTICLES. (R823980)
Citation:
Johnston, M. V. AND A. S. Wexler. MASS SPECTROMETRY OF INDIVIDUAL AEROSOL PARTICLES. (R823980). Analytical Chemistry. American Chemical Society, Washington, DC, 67:721A-726A, (1995).
Description:
Typically, in real-time aerosol mass spectrometry (RTAMS), individual airborne particles
are ablated and ionized with a single focused laser pulse. This technique yields information that
permits bulk characterization of the particle, but information about the particle's surface is often
masked or diluted by the particle bulk. Here we show that it is possible to probe the surface
composition of individual airborne particles by separating the desorption and ionization steps using a
two-laser real-time aerosol mass spectrometry technique (L2RTAMS). First, a weak excimer laser
pulse was used to desorb the semivolatile components of the particle surface when the particle was in
the center of the ion trap. After a short delay, another excimer laser pulse was used to ionize the
semivolatile surface components in the gas phase and subsequently mass analyzed. The results from
the one- and two-laser techniques were compared and found to be complementary. The L2RTAMS
technique was found very sensitive to polycyclic aromatic hydrocarbons (PAHs). PAHs, of the type
emitted from diesel engines, were found on particle surfaces of National Institute of Standards and
Technology (NIST) standard reference materials (SRMs) from Indiana Harbor Canal (1645) and
urban particulate matter (1648). PAH partitioning on the environmental particles is discussed. (27
References)