Characterization of organic compounds in 10- to 50-nm aerosol particles in boreal forest with laser desorption-ionization aerosol mass spectrometer and comparison with other techniques

The aim of this study was to characterize the organic composition of ambient ultrafine particles (<50 nm) in a boreal forest environment and compare the analytical results obtained by different techniques with use a data analysis software. In the chromatographic techniques, particles were collected on a filter and analyzed off-line after sample preparation, whereas in the aerosol MS, particle analysis was performed directly from the particle source. ompounds and chemical groups were identified with a laser aerosol mass spectrometer (laser AMS) and selected organic compounds, including acids, polyols, amines and aldehydes, from 50 nm filter samples were quantified. Interesting components found with the laser AMS included oxygenated and aliphatic hydrocarbons, aromatic compounds, amines, and black carbon. The amines found on laser AMS may be related to new particle formation events at particle sizes 10–25 nm. Correlations between the results obtained with different instruments were clarified, and the best correlations were found between laser AMS and 50-nm size filter samples. There were no correlations between the laser AMS data and meteorological data or on-line measured gas phase compounds. The black carbon found on laser AMS had moderate correlation for levoglucosan found on all-sized filter samples. Finally, the correlation analysis revealed that the information obtained from sub-50-nm size range particles and results for particles several times higher could not be directly compared.