Technical Note: An Automated System for Separate Combustion of Elemental and Organic Carbon for C-14 Analysis of Carbonaceous Aerosol

We present the design and evaluation of an automated system for the conversion of elemental and organic carbon aerosol to CO2 for subsequent radiocarbon analysis. The system allows heating the sample in pure oxygen or helium at user defined temperature steps, followed by catalytic conversion of incomplete carbonaceous combustion products to CO2. The resulting CO2 is quantified using an NDIR detector and can be separated from other combustion by-products in a reduction oven. The purified CO2 is cryogenically collected in glass ampoules that can be sealed for storage until C-14 analysis. We show that (1) the CO2 amount measured by the calibrated NDIR sensor compares well to an independent manometric method, (2) that we successfully remove combustion by-products such as SO2, H2O, and NOx, resulting in pure CO2 samples, and (3) that the system has low contamination and negligible cross contamination making it ideal for the analysis of very small samples in the order of 10-50 mu gC.