AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Laser Ablation Aerosol Mass Spectrometry for Molecular Analysis of Biological Materials
LIZABETH ALEXANDER, Matthew Newburn, Douglas Day, Jose-Luis Jimenez, Manjula Canagaratna, Douglas Worsnop, Vanessa Bailey, Pacific Northwest National Laboratory
Abstract Number: 656 Working Group: Instrumentation and Methods
Abstract We report on fundamental studies in the development of a laser ablation micro-sampling system coupled with aerosol mass spectrometry (LA-AMS) for micron scale characterization of microbial and other biogeochemical samples. This work extends existing laser ablation techniques, originally developed for geological and other refractory inorganic samples, to biological and other organic sample matrices. Geological analyses by laser ablation typically involve elemental and isotopic detection by ICP-MS/AES. Research in this field over the last decade established that laser ablation of refractory samples using UV wavelengths with pulse lengths below 10 ns results in the production of particles whose composition is representative of the solid material which are therefore suitable for elemental analysis with ICP-MS/AES.
Results are presented which demonstrate that laser ablation of biological and organic sample matrices by nanosecond UV commercial laser ablation systems at 193 And 266 nm (Photon Machines Analyte G2 and Cetac LSX-500) results in the production of particulates which preserve molecular information representative of the solid sample. We have characterized particle size distributions using both an SMPS and a high resolution time-of-flight aerosol mass spectrometer (Aerodyne HR-ToF-AMS) and observed a mass-weighted peak from 100 to 200 nm, an ideal size range for quantitative transport from the ablation cell to the AMS. The HR-ToF-AMS was also used to demonstrate that molecular information from complex biological and organic samples is preserved and can be used to characterize a given sample matrix using the detailed suite of statistical methods and software developed for the characterization of atmospheric aerosols. Initial data is presented using this new LA-AMS method to generate chemical images of biological samples including soil aggregates and actively growing fungi at resolutions down to 5 microns. These data also provide insights into the mechanism of particle formation by laser ablation in biological sample matrices.