Stable Carbon Isotope Ratio Analysis of Anhydrosugars in Biomass Burning Aerosol Particles from Source Samples

A new method for stable carbon isotope ratio analysis of anhydrosugars from biomass burning aerosol particle source filter samples was developed by employing Thermal Desorption 2 Dimensional Gas Chromatography Isotope Ratio Mass Spectrometry (TD-2DGC-IRMS). Compound specific isotopic measurements of levoglucosan, mannosan, and galactosan performed by TD-2DGC-IRMS in a standard mixture show good agreement with isotopic measurements of the bulk anhydrosugars, carried out by Elemental Analyzer Isotope Ratio Mass Spectrometry (EA-IRMS). The established method was applied to determine the isotope ratios of levoglucosan, mannosan, and galactosan from source samples collected during combustion of hard wood, softwood, and crop residues delta C-13 values of levoglucosan were found to vary between -25.6 and -22.2%o, being higher in the case of softwood. Mannosan and galactosan were detected only in the softwood samples showing isotope ratios of -23.5%o (mannosan) and -25.7%o (galactosan). The isotopic composition of holocellulose in the plant material used for combustion experiments was determined with delta C-13 values between -28.5 and -23.7%o. The difference in delta C-13 of levoglucosan in biomass burning aerosol particles compared to the parent fuel holocellulose was found to be -1.89 (+/- 0.37)parts per thousand for the investigated biomass fuels. Compound specific delta C-13 measurements of anhydrosugars should contribute to an improved source apportionment.