Grantee Research Project Results
Final Report: Ion Mobility Analysis of Particulate Matter and Gas Phase Precursors
EPA Grant Number: R832836Title: Ion Mobility Analysis of Particulate Matter and Gas Phase Precursors
Investigators: Wexler, Anthony S.
Institution: University of California - Davis
EPA Project Officer: Chung, Serena
Project Period: March 6, 2006 through March 5, 2009 (Extended to March 5, 2011)
Project Amount: $372,168
RFA: Continuous Measurement Methods for Particulate Matter Composition (2005) RFA Text | Recipients Lists
Research Category: Particulate Matter , Air Quality and Air Toxics , Air
Objective:
A new cost-effective and portable instrument for analyzing the semi-volatile organic and inorganic gas phase precursors.
Summary/Accomplishments (Outputs/Outcomes):
- A paper was published on the theoretical basis for the instrument and its testing in a low resolution configuration.
- Many versions of a high-resolution prototype were built with the goal of testing a design that is cheap to manufacture. A version that uses a sandwich of printed circuit boards was settled on.
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The ionizer in these versions was originally 63Ni, which caused a number of problems
- since the source is a long-lived radionuclide, it had permitting and contamination problems.
- the ionization efficiency was low because the mean free path for the beta particles was much larger than the container housing the foil.
- the beta particles also ionize water which caused numerous artifacts in the spectra with multiple analyte-hydrates forming.
- The 63Ni ionizer was replaced with a UV photoionization source which mitigated all of these problems.
e.Difficulties finding an electrometer array with sufficient sensitivity persisted. TSI loaned us a 22-channel electrometer but this was insufficient for the instrument since it uses macroscopic components. A new partnership has been developed with a company that manufactures an electrometer array on a chip
Conclusions:
Inexpensive, real-time instruments enable much more spatially dense monitoring of ambient concentrations and real-time assessment of their temporal variability. These are very important to health effects studies and identifying sources. Although we were not able to complete development and testing of CF-IMS during the period of this grant, work on it continues.
The main objective for the subsequent work is to partner with a company that makes sensitive solid state electrometers for recording the CF-IMS ion signal. The agreement for this partnership is in place and we are rebuilding the low-voltage CF-IMS manifold to accommodate this electrometer array. Once completed, the company will visit us to help us use the array and debug the resulting instrument. A manuscript demonstrating capabilities, including sensitivity and resolution, will be written and submitted for publication. Testing of the CF-IMS and industry partnering to advance the design to field deployment continue.
Journal Articles:
No journal articles submitted with this report: View all 5 publications for this projectSupplemental Keywords:
Scientific Discipline, Air, Environmental Chemistry, Environmental Monitoring, Engineering, Chemistry, & Physics, atmospheric measurement, monitoring, ion mobility spectrometer, aerosol particles, air sampling, chemical composition, chemical detection techniques, field monitoring, particulate matter chemistry, atmospheric aerosolsProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.
Project Research Results
- 2009 Progress Report
- 2008 Progress Report
- 2007 Progress Report
- 2006 Progress Report
- Original Abstract
1 journal articles for this project