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Hatcher Presents Research in Switzerland Highlighting ODU's Cutting-Edge Chemical Analysis

Patrick Hatcher, the Old Dominion University Batten Endowed Chair in Physical Sciences, delivered an invited talk highlighting ODU's work in analytical chemistry at the Goldschmidt 2009 Conference, "Challenges to Our Volatile Planet," during the last week of June in Davos, Switzerland.

"Molecular Characterization of Atmospheric Particulates Using Fourier Transform Ion Cyclotron Resonance (FT-ICR) Mass Spectrometry" was the title of Hatcher's presentation. In it, he described new molecular-level characterization of atmospheric particulates that is made possible by the College of Sciences Major Instrumentation Cluster (COSMIC) Laboratory.

Scientists have known that humic-like substances are a major component of atmospheric particulates. But molecular-level characterization of the substances has been limited in the past to compounds that have been extracted by organic solvents or compounds that have been chemically and thermally degraded from their original large and complicated form.

The Hatcher research group recently introduced a new approach to molecular-level studies of humic substances from soils and natural waters. The approach utilizes FT-ICR mass spectrometry and strategies Hatcher has developed to get the most data from this type of analysis.

Now, their studies of diesel exhaust and aerosols, including some produced by natural vegetation fires, have identified molecules originating from combustion, as well as compounds originating from vegetation or soil. In the particulates, the researchers have found soot or black carbon-derived compounds that contain sulfur or nitrogen and have noted that nitric acid oxidation of diesel exhaust and atmospheric particulates tends to enhance the production of these compounds.

Researchers from ODU's Department of Chemistry and Biochemistry who worked with Hatcher on the studies reported at Goldschmidt 2009 are Rachel Sleighter, a Ph.D. student, as well as Assistant Professor Paula Mazzer and her master's student, Amanda Willoughby, whose thesis work concerns nitric acid oxidation. Other collaborators are Andrew Wozniak and James Bauer of the Virginia Institute of Marine Sciences.

"Our new approach for molecular characterization of the humic-like molecules in atmospheric particulates will revolutionize our understanding of the chemistry of these substances and can lead us to better understanding of their role in atmospheric processes," Hatcher said.

Atmospheric particulates are very small particles of solids or liquids suspended in air, coming from natural sources such as volcanoes and wind-blown dirt or manmade sources such as smoke from factories and the exhaust of motor vehicles. In the case of humic-like molecules, the particulates chemically resemble the decayed plant and animal matter that forms the humus of soils.

All particulates in the air can influence rainfall and global temperatures, in some cases making the Earth cooler and in others making it warmer, and are therefore of interest to scientists studying climate change. The Goldschmidt 2009 Conference, presented by the Geochemical Society and the European Association of Geochemistry, brought together international experts in the chemistry of the Earth to present and debate the latest research related to "Challenges to Our Volatile Planet."

The COSMIC Lab, which Hatcher manages, was formed and an ultra-high resolution 12-Tesla FT-ICR mass spectrometer was purchased for nearly $1.5 million soon after Hatcher joined the university in 2005.

Hatcher and his research group at ODU have used the FT-ICR mass spectrometer, as well as nuclear magnetic resonance instruments, for a broad range of research, including studies focusing on the environment. He has been an innovator in research on hard-to-analyze organic molecules that are typically very large and complicated.

FT-ICR mass spectrometry provides chemical analysis by means of a sample's molecules being ionized (electrically charged) and transferred to a cell in a strong magnetic field, which causes the ions to travel in circular orbits in the cell with a frequency that is inversely related to the molecular weight of the ions divided by the charge (usually +1). Because the frequency of the orbits can be measured very accurately, the molecular weight can be measured very accurately, usually to within 5 decimal places.

This article was posted on: July 8, 2009

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