δ13C analysis of bulk organic matter in speleothems using liquid chromatography-isotope ratio mass spectrometry

The determination of delta C-13 values in speleothems is of considerable importance in palaeoenvironmental research, but has focussed solely on analysis of the carbonate. Here we demonstrate a new method for analysing the delta C-13 values of organic matter (OM) trapped in speleothems, utilising flow injection liquid chromatography-isotope ratio mass spectrometry (LC- IRMS). Developmental analysis using a homogenised speleothem powder showed that the method is robust, with repeated digests and analyses having an average standard deviation of 0.1 parts per thousand. Dilution tests with samples of 4-23 mu g total organic carbon (TOC) show relatively small linearity effects, with the overall standard deviation across a peak response range of 1700-9000 mV being 0.2%. (C) 2012 Elsevier Ltd. All rights reserved.