Determination of the concentration and stable isotopic composition of oxygen in organic matter containing carbon, hydrogen, oxygen, nitrogen, and sulfur

A method for the quantitative production of carbon dioxide from oxygen in organic matter consisting of carbon, hydrogen, oxygen, nitrogen, and sulfur has been developed. Manometric and mass spectrometric analysis of the CO_2 permit direct determination of the concentration and isotopic composition of oxygen in CHONS compounds with accuracy comparable to that previously achievable for CHO and CHON compounds. Samples containing as little as 187 µmol of oxygen with S/O ratios as high as 0.16 have been analyzed by using this method