Dr. Roy Dixon

Doctor of Philosophy in Environmental/Analytical Chemistry
University of Washington    7/91

Bachelor of Science in Chemistry  
University of California    6/84

Chem. 31 – Quantitative Analysis
Chem. 133 – Chemical Instrumentation
Chem. 4 – Chemical Calculations

A.  Aerosol-Based HPLC Detectors.
    While high performance liquid chromatography (HPLC) is one of the most commonly employed separation techniques, there is not yet a universal, low cost detector.  We have been working on the development and improvement of aerosol-based detectors for HPLC.  Aerosol-based detectors function by converting compounds exiting the HPLC column to aerosol particles which are detected using conventional aerosol technology.  Past aerosol-based detectors have used particle light-scattering for aerosol detection (commonly known as evaporative light scattering detection or ELSD).  We have developed a detection method we called aerosol charging detection (ACD) which is more efficient method for detecting small particles resulting in better sensitivity.  A commercial detector, the charged aerosol detector, recently has been marketed that employs this technology and won a Pittcon award and an R&D100 award in 2005. We now are investigating alternative methods of charging aerosol particles that do not utilize a high voltage corona discharge source.

B.  Analysis of Atmospheric Aerosols.
    Atmospheric aerosols significantly affect visibility and the earth’s climate by their light scattering properties and have health effects in regions of high concentrations.  However, the sources of the organic fraction of aerosols is not well known in many regions.  We have been working on developing methods to identify specific organic compounds using HPLC-ACD.  This work has centered on the analysis of monosaccharide anhydrides (e.g. levoglucosan), which are compounds emitted from biomass combustion.  We have been analyzing air samples influenced by wood smoke from home heating and smoke from forest fires to assess the affects of these sources on air quality.

Ward, T. J., R. F. Hamilton, Jr., R. W. Dixon, M. Paulsen, and C. D. Simpson, “Characterization and evaluation of smoke tracers in PM: Results from the 2003 Montana wildfire Season”, accepted for publication in Atmospheric Environment, June, 2006.

Dixon, R. W. and G. Baltzell, "Determination of Levoglucosan in Atmospheric Aerosols Using High Performance Liquid Chromatography with Aerosol Charge Detection", Journal of Chromatography A, 1109, 214-221, 2006.

Dixon, R. W. and D. S. Peterson, "Development and testing of a detection method for liquid chromatography based on aerosol charging", Analytical Chemistry, 74, 2930-2937, 2002.

Dixon, R. W., K. Goodwin, R. Wong, and W. DeGraffenreid, “Effects and use of spray electrification in aerosol charge detection for HPLC, ” oral presentation at the 30th International Symposium on High Performance Liquid Phase Separations and Related Techniques, San Francisco, CA, June, 2006.

Wong, R. H. F. and R. W. Dixon, "An investigation of charging modes in an aerosol chage detector for HPLC," Poster Presentation given by R. Dixon at the 18th Annual CSU Biotechnology Symposium, San Jose, CA, January, 2006.

Goodwin, K. N., R. H. F. Wong, R. W. Dixon, and W. DeGraffenreid "Development of an economical detector for HPLC utilizing spray electrification," Poster Presentation at the 18th Annual CSU Biotechnology Symposium, San Jose, CA, January, 2006.

Dixon, R. W., “Measurement of Carbohydrates in Aerosols from Forest Fires and Residential Wood Burning”, invited presentation for UC Davis Agricultural and Environmental Chemistry Graduate Group, October, 2005.

Dixon, R. W., G. Baltzell, J. R. Cruz, A. C. Rios, E. Vidrio, and K. K. Whitfield, "Use of HPLC with an Aerosol Charge Detector for the Analysis of Carbohydrates", Western Regional Meeting of the American Chemical Society, October, 2004.

Cruz, J. R. and R. W. Dixon, "Residential Wood Combustion in California Central Valley Cities and the Sierra Nevada Mountains during Winter”, Western Regional Meeting of the American Chemical Society, October, 2004.

Dixon, R. W. and J. R. Cruz, "Measurement of monosaccharide anhydrides in ambient aerosols for estimation of the wood smoke component," Oral presentation at the International State of the Science Workshop on Organic Speciation in Atmospheric Aerosols Research, Las Vegas, NV, April, 2004.

Dixon, R. W. and G. Baltzell, "A High Performance Liquid Chromatography Method for Determination of Levoglucosan Concentrations in Atmospheric Aerosols", poster presentation at the Fall, 2002 Meeting of the American Geophysical Union.

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