Graphitisation of CO2 for radiocarbon analysis
Radiocarbon, especially in small samples, is now typically measured by accelerator mass spectrometry (AMS). This requires that the carbon, for example from a carbonate shell sample, be concentrated in graphite form, allowing it to be easily ionised and to produce a strong current for AMS analysis. More information on the graphitisation method we use is available here.
Our lab set-up consists of a hydrogen/iron catalyst system for reducing CO2 to graphite at high temperature (550oC) (see Freeman et al., 2016). The lab was built in 2009/2010 with funding from the Royal Society and support from various friendly AMS folk from around the world (follow this link to see how it was set up). We work mainly with small carbonate samples, but can in principle reduce any CO2 that can be introduced into the vacuum line via the ‘cracking’ of sealed glass tubes or needle penetration of septum-sealed vials. For the most part this lab serves to facilitate research into past ocean circulation and marine carbon cycling.
You can find some more information on radiocarbon dating and the use of radiocarbon as a carbon cycle tracer via the very informative AMS lab links below.
More information on AMS dating in the UK:
University Oxford Radiocarbon Accelerator Unit, University of Oxford
NERC Radiocarbon facility, East Kilbride