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Thermal desorption-multiphoton ionization time-of-flight mass spectrometry of individual aerosol particles: A simplified approach for online single-particle analysis of polycyclic aromatic hydrocarbons and their derivatives.
Anal. Chem. 81, 2525-2536 (2009)
Online single-particle (SP) laser mass spectrometry (MS) is an important tool for fundamental and applied aerosol research. Usually laser desorption/ionization (LDI) is applied for ablation and ionization of atoms and molecular fragments from the nanometer- or micrometer sized air-borne particles and time-of-flight analysers (TOFMS) are used for mass-selective detection of mainly inorganic analytes. The detection of molecular organic compounds is solely possible under very special experimental conditions and extremely dependent on the particle matrix and thus limited to special applications. Very recently it was shown that by implementation of a two-step laser desorption (LD) resonance-enhanced multiphoton ionization (REMPI) postionization approach the single-particulate molecular signature of polycyclic aromatic hydrocarbons (PAH) and their derivatives can be recorded (LD-REMPI-SP-TOFMS). By this, particles from different sources could be differentiated via the patterns of s pecific molecular source tracers such as retene for soft wood combustion or larger PAH as indicator for gasoline car emissions. One drawback of the LD-REMPI-SP-TOFMS method-in particular for field applications-is, however, the necessity of operation and adjustment of two lasers. In this paper the successful implementation of a thermal desorption step in single-particle mass spectrometry is described (TD-REMPI-SP-TOFMS). After size determination by particle velocimetry, individual particles are thermally desorbed on a heated surface in the ion source of the TOFMS. Desorbed molecules are ionized subsequently by REMPI, which addresses selectively PAH and molecular trace indicators. The TD-REMPI-SP-TOFMS concept Is tested with reference particles and applied for automotive exhaust and ambient monitoring. The comparison of the results with the ones obtained by the two-laser approach (LD-REMPI-SP-TOFMS) indicates that the patented TD-REMPI-SP-TOFMS technology presented here is nearly equally well suited for studying organic source tracers in ambient aerosols and aerosol emissions. The increased ruggedness and simplicity of the new approach, however, may favor its application for field measurements in aerosol science and technology.
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Publikationstyp
Artikel: Journalartikel
Dokumenttyp
Wissenschaftlicher Artikel
Schlagwörter
performance liquid-chromatography; particulate air-pollution; peak expiratory flow; source apportionment; laser desorption/ionization; organic-compounds; fine particles; atmospheric particles; spectral signatures; surface ionization; thermal desorption; individual aerosol particles; polycyclic aromaatic hydrocarbons
ISSN (print) / ISBN
0003-2700
e-ISSN
1520-6882
Zeitschrift
Analytical Chemistry
Quellenangaben
Band: 81,
Heft: 7,
Seiten: 2525-2536
Verlag
American Chemical Society (ACS)
Nichtpatentliteratur
Publikationen
Begutachtungsstatus
Peer reviewed
Institut(e)
Institute of Ecological Chemistry (IOEC)
Cooperation Group Comprehensive Molecular Analytics (CMA)
Cooperation Group Comprehensive Molecular Analytics (CMA)