Copyright © 2006 American Chemical Society
Web Release Date: April 13,
Fast Determination of the Relative Elemental and Organic Carbon Content of Aerosol Samples by On-Line Single-Particle Aerosol Time-of-Flight Mass Spectrometry
GSF-Forschungszentrum, Institut für Ökologische Chemie, Ingolstädter Landstrasse 1, 85764 Neuherberg, Germany, Analytische Chemie, Lehrstuhl für Festkörperphysik, Institut für Physik, Universität Augsburg, Universitätsstrasse 1, 86159 Augsburg, Germany, GSF Forschungszentrum, Institut für Inhalationsbiologie, Ingolstädter Landstrasse 1, 85764 Neuherberg, Germany, Lawrence Livermore National Laboratory, 7000 East Avenue, L211, Livermore, California 94550, and BifA-Bayerisches Institut für Umweltforschung und technik, Abteilung Umwelt und Prozesschemie, Am Mittleren Moos 46, 86167 Augsburg, Germany
Received for review April 26, 2005
Revised manuscript received January 16, 2006
Accepted January 28, 2006
Different particulate matter (PM) samples were investigated by on-line single-particle aerosol time-of-flight mass spectrometry (ATOFMS). The samples consist of soot particulates made by a diffusion flame soot generator (combustion aerosol standard, CAST), industrially produced soot material (printex), soot from a diesel passenger car as well as ambient particulates (urban dust (NIST) and road tunnel dust). Five different CAST soot particle samples were generated with different elemental carbon (EC) and organic carbon (OC) content. The samples were reaerosolized and on-line analyzed by ATOFMS, as well as precipitated on quartz filters for conventional EC/OC analysis. For each sample ca. 1000 ATOFMS single-particle mass spectra were recorded and averaged. A typical averaged soot ATOFMS mass spectrum shows characteristic carbon cluster peak progressions (Cn+) as well as hydrogen-poor carbon cluster peaks (CnH1-3+). These peaks are originated predominately from the elemental carbon (EC) content of the particles. Often additional peaks, which are not due to carbon clusters, are observed, which either are originated from organic compounds (OC-organic carbon), or from the non-carbonaceous inorganic content of the particles. By classification of the mass spectral peaks as elemental carbon (i.e., the carbon cluster progression peaks) or as peaks originated from organic compounds (i.e., molecular and fragment ions), the relative abundance of elemental (EC) and organic carbon (OC) can be determined. The dimensionless TC/EC values, i.e., the ratio of total carbon content (TC, TC = OC + EC) to elemental carbon (EC), were derived from the ATOFMS single-particle aerosol mass spectrometry data. The EC/TC values measured by ATOFMS were compared with the TC/EC values determined by the thermal standard techniques (thermooptical and thermocoulometric method). A good agreement between the EC/TC values obtained by on-line ATOFMS and the off-line standard method was found.