Grantee Research Project Results
1999 Progress Report: Development, Evaluation, and Application of a Fast Time Response Mass Spectrometric Method for Quantitative Monitoring of Oxidant Precursors
EPA Grant Number: R825256Title: Development, Evaluation, and Application of a Fast Time Response Mass Spectrometric Method for Quantitative Monitoring of Oxidant Precursors
Investigators: Shepson, Paul
Institution: Purdue University
EPA Project Officer: Hahn, Intaek
Project Period: October 1, 1996 through September 30, 1999 (Extended to October 30, 2000)
Project Period Covered by this Report: October 1, 1998 through September 30, 1999
Project Amount: $440,262
RFA: Air Quality (1996) RFA Text | Recipients Lists
Research Category: Air Quality and Air Toxics , Air
Objective:
The principal objective of this research effort is to develop and evaluate an MS/MS method for fast detection of ozone precursors. The focus during this grant period has been on biogenic hydrocarbons, specifically isoprene, its oxidation products (e.g., methyl vinyl ketone and methacrolein), and terpenes. This project focuses on development of methods based on chemical ionization coupled with ion trap mass spectrometry, to enable rapid, selective and sensitive determination of a variety of VOCs in a complex mixture.Progress Summary:
In the third year of this effort, we focused on interpretation and dissemination of results from the Year 2 field study conducted as part of the Program for Research on Oxidants: Photochemistry, Emissions, and Transport (PROPHET), as well as participation in the Southern Oxidants Study in the Nashville, TN, area. A key accomplishment of this research project has been development of a novel chemical ionization quadrupole ion trap MS/MS method for rapid determination of atmospheric isoprene concentrations. Fast time measurements of isoprene are important due to the short chemical lifetime of isoprene in the daytime (as short as ~1/2 hour), and the need for reliable aircraft-based measurement methods. Our method relies on reaction of the methyl vinyl ether radical cation with isoprene in the ion source, to yield a mass 94 adduct, that is then isolated in the ion trap followed by collisional dissociation to produce protonated benzene that is then detected. The selectivity afforded by this method allows us to determine isoprene without prior chromatographic separation. The fundamentals of the method were reported in Colorado et al. (1998).
In the summer of 1998, we had an opportunity to test this method under field conditions as part of the PROPHET (see: http://aoss.engin.umich.edu/PROPHET/) field campaign. During that study, the ion trap conducted measurements of isoprene, side-by-side with four other independent methods, for a 6-week period in summer. Three of those methods were GC/MS methods, while one was a unique ozone-chemiluminescence method. As a result, we were able to construct an informal isoprene measurement intercomparison study. The results have been analyzed, and are being reported in Barket et al. (2000). That paper, written by graduate student Dennis Barket, is part of a special section of J Geophys Res on the PROPHET program, that is scheduled for publication in late 2000. The intercomparison indicated that the ion trap method has great potential, but also revealed some important weaknesses that are currently being addressed.
During PROPHET98, we discovered that there are substantial concentrations of OH radicals in the atmosphere above the forest canopy in the evening. This discovery helps explain our observation that there is rapid nighttime decay of isoprene at this site. The interpretation of this data and the nighttime behavior of isoprene is reported in Hurst et al. (2000), which is a paper prepared by my graduate student, Julia Hurst, for the PROPHET special section. To follow up on the observations of active nighttime radical chemistry at PROPHET, we conducted measurements of a variety of biogenic and anthropogenic VOCs as part of the Nashville Southern Oxidants campaign in the summer of 1999. We currently are in the process of analyzing that data.
Future Activities:
At this point, our future activities will focus on preparation of manuscripts associated with interpretation of the field data obtained as part of the PROPHET and SOS field campaigns.Journal Articles on this Report : 3 Displayed | Download in RIS Format
| Other project views: | All 20 publications | 6 publications in selected types | All 6 journal articles |
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Barket Jr. DJ, Hurst JM, Couch TL, Colorado A, Shepson PB, Riemer DD, Hills AJ, Apel EC, Hafer R, Lamb BK, Westberg HH, Farmer CT, Stabenau ER, Zika RG. Intercomparison of automated methodologies for determination of ambient isoprene during the PROPHET 1998 summer campaign. Journal of Geophysical Research–Atmospheres 2001;106(D20):24301-24313. |
R825256 (1999) R825256 (Final) R825257 (Final) R825419 (Final) |
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Colorado A, Barket Jr. DJ, Hurst JM, Shepson PB. A fast-response method for determination of atmospheric isoprene using quadrupole ion trap mass spectrometry. Analytical Chemistry 1998;70(24):5129-5135. |
R825256 (1999) R825256 (Final) |
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Hurst JM, Barket Jr. DJ, Herrera-Gomez O, Couch TL, Shepson PB, Faloona I, Tan D, Brune W, Westberg H, Lamb B, Biesenthal T, Young V, Goldstein A, Munger JW, Thornberry T, Carroll MA. Investigation of the nighttime decay of isoprene. Journal of Geophysical Research–Atmospheres 2001;106(D20):24335-24346. |
R825256 (1999) R825256 (Final) R825419 (Final) |
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Supplemental Keywords:
measurement methods, Great Lakes., RFA, Air, Scientific Discipline, Geographic Area, Toxics, EPA Region, State, tropospheric ozone, VOCs, Atmospheric Sciences, air toxics, air quality data, air sampling, mass spectrometry, environmental monitoring, measurement of oxygenated compounds, rapid sampling and analysis, Indiana, atmospheric monitoring, monitoring, Region 5, ambient air, ambient ozone data, field measurements, ozone, quantitative monitoring of oxidant precursors, IN, Michigan (MI)Relevant Websites:
http://aoss.engin.umich.edu/PROPHET/ 
http://www.chem.purdue.edu/shepson/shephome.html
Progress 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.