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

Xue F. Sang, Iulia Gensch, Werner Laumer, Beatrix Kammer. Chuen Y. Chan, Guenter Engling, Andreas Wahner, Holger Wissel, A. Kiendler-Scharr

Abstract

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. δ¹³C values of levoglucosan were found to vary between −25.6 and −22.2‰, being higher in the case of softwood. Mannosan and galactosan were detected only in the softwood samples showing isotope ratios of −23.5‰ (mannosan) and −25.7‰ (galactosan). The isotopic composition of holocellulose in the plant material used for combustion experiments was determined with δ¹³C values between −28.5 and −23.7‰. The difference in δ¹³C of levoglucosan in biomass burning aerosol particles compared to the parent fuel holocellulose was found to be −1.89 (±0.37)‰ for the investigated biomass fuels. Compound specific δ¹³C measurements of anhydrosugars should contribute to an improved source apportionment.