Treatment of small samples of particulate organic carbon (POC) for radiocarbon dating of ice

A filtration method for radiocarbon determination on particulate organic carbon (POC) in glacier ice is explored at VERA (Vienna Environmental Research Accelerator). Previous work on true samples has shown that laboratory contamination is the limiting factor. By systematic investigations on the origin of carbon contamination, we were able to reduce the background significantly. In two first measurements using artificially produced clean ice a blank level as low as 1.3 μgC/kg ice could be achieved. These results were obtained by a simplified combustion scheme using valve-sealed vials. The combustion yield for organic materials was found to be 80% with a very low background typically below 1 μgC. Outliers turned out to be the main obstacle when dealing with such minute carbon amounts.