2009 Progress Report: Characterization and Source Apportionment

EPA Grant Number: R832415C001
Subproject: this is subproject number 001 , established and managed by the Center Director under grant R832415
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: Rochester PM Center
Center Director: Oberdörster, Günter
Title: Characterization and Source Apportionment
Investigators: Hopke, Philip K. , Gelein, Robert , Prather, Kimberly A.
Institution: Clarkson University , University of California - San Diego , University of Rochester
EPA Project Officer: Chung, Serena
Project Period: October 1, 2005 through September 30, 2010 (Extended to September 30, 2012)
Project Period Covered by this Report: October 1, 2008 through September 30,2009
RFA: Particulate Matter Research Centers (2004) RFA Text |  Recipients Lists
Research Category: Health Effects , Air

Objective:

 

Progress Summary:

Research on the characterization of urban ultrafine and accumulation mode particles allows composition and size analysis in real time of single particles using aerosol time-of-flight mass spectrometry (ATOFMS).  The objective of the research is to greatly expand the understanding of the chemical composition and impact of specific sources of ultrafine particles on human health.  The ATOFMS has been connected to the UR ultrafine particle concentrator.  In order to improve the hit rate for particles, a growth tube was used.  The growth tube works on the same principle as used in the water-based condensation particle counter.  Particle mass spectra have been collected and work is underway to interpret the results
 
Prior work has identified the presence of particle-bound reactive oxygen species (ROS) in ambient PM.  These initial measurements were made with a manual sampling and analysis system.  We have now developed an automated system that would provide continuous measurements of particle-bound ROS.  The laboratory system has now been engineered to be a field monitor that was deployed in Rochester in the August 2009.  The time series of initial measurements is shown in Figure 1.
 
In addition, work has continued on the characterization of the important ROS species.  A method for their detection and characterization is needed to preserve these radicals for a sufficiently long time to permit analyses to be performed.  Radical-addition reactions, also called spin trapping techniques, allow the detection of short-lived radicals.  This approach has been applied to products from the α-pinene/ozone reaction.  Secondary organic aerosol (SOA) from a reaction chamber was collected on quartz fiber filters and extracted with a solution of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) (spin trap) followed by analysis with ion-trap tandem mass spectrometry (MSn) using electrospray ionization (ESI) in the positive scan mode.  The DMPO adducts with radical species appear as positive ions [DMPO-R+H]+, [DMPO-OR+H]+ and [DMPO-O-OR+H]+ in full MS spectra of the samples.  Tandem mass spectrometry (MS2) was performed to identify the radical species.  The DMPO adducts with the C-centered radical species [DMPO-R+H]+ are characterized by m/z 114 [DMPO+H]+ in the MS2 spectra and with peaks that represent the loss of [DMPO+H]+.  The DMPO adducts with O-centered radical species (RO· and ROO·) are identified by m/z 130 [DMPO-OH+H]+ and m/z 146 [DMPO-O-OH+H]+ ions, respectively, and with peaks that correspond to the loss of those adducts.  DMPO was also able to capture OH radicals from the particle phase, and the product ion fragmentation confirmed DMPO/OH structure providing evidence for particle-bound OH radicals.  A manuscript describing this work is currently under review at Atmospheric Chemistry and Physics.

Future Activities:

During the next year, we will continue to use spin traps to explore the nature of the initially formed free radical species that form an important part of the reactive oxygen species associated with freshly formed secondary organic aerosols.  We are also making ambient measurements using the spin traps in urban and rural environments to explore the presence of particle-bound free radical species.  We are also exploring the potential use of new fluorogenic probes for the ROS measurement.  Recently, Fairfull-Smith and Bottle (2008) have reported a series of new probes that appear to be more sensitive and with less blank problems than the dichlorofluorescin-based system we are currently using.  We are working with Prof. Bottle to test his probes as we did with the other currently used probes (Venkatachari and Hopke, 2008a).  They claim that their probes will be as sensitive, but with lower and more consistent blank values and without the self-oxidation seen with DCFH.  The first batch of the probe is to be sent from the Queensland University of Technology to permit the initial experiments to be performed.

References:

Fairfull-Smith, K.E., Bottle, S.E., (2008) The Synthesis and Physical Properties of Novel Polyaromatic Profluorescent Isoindoline Nitroxide Probes, European Journal of Organic Chemistry 2008 (32), 5391-5400.   


Journal Articles on this Report : 1 Displayed | Download in RIS Format

Other subproject views: All 19 publications 13 publications in selected types All 13 journal articles
Other center views: All 190 publications 156 publications in selected types All 143 journal articles
Type Citation Sub Project Document Sources
Journal Article Pavlovic J, Hopke PK. Technical note: detection and identification of radical species formed from α-pinene/ozone reaction using DMPO spin trap. Atmospheric Chemistry and Physics Discussions 2009;9(6):23695-23717. R832415 (2009)
R832415 (2010)
R832415 (2011)
R832415 (Final)
R832415C001 (2009)
R832415C001 (2010)
R832415C001 (2011)
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  • Supplemental Keywords:

    RFA, Scientific Discipline, Air, particulate matter, Health Risk Assessment, Environmental Chemistry, Biochemistry, airway epithelial cells, atmospheric particles, cardiopulmonary responses, chemical characteristics, fine particles, airborne particulate matter, aerosol composition, human exposure

    Progress and Final Reports:

    Original Abstract
  • 2006 Progress Report
  • 2007 Progress Report
  • 2008 Progress Report
  • 2010 Progress Report
  • 2011 Progress Report
  • Final Report

  • Main Center Abstract and Reports:

    R832415    Rochester PM Center

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R832415C001 Characterization and Source Apportionment
    R832415C002 Epidemiological Studies on Extra Pulmonary Effects of Fresh and Aged Urban Aerosols from Different Sources
    R832415C003 Human Clinical Studies of Concentrated Ambient Ultrafine and Fine Particles
    R832415C004 Animal models: Cardiovascular Disease, CNS Injury and Ultrafine Particle Biokinetics
    R832415C005 Ultrafine Particle Cell Interactions In Vitro: Molecular Mechanisms Leading To Altered Gene Expression in Relation to Particle Composition