Continuous Flow Isotope Ratio Mass Spectrometry GasBench: CO2, N2O Gas Chromatograph-Combustion: CO2, N2, H2 Step #1: Convert organic or inorganic samples into gas. d13C… CO2 d15N… N2 d2H… H2 d18O… CO d34S… SO2 Elemental Analyzer (EA): N2, CO2, SO2 Thermal Conversion–EA (TCEA): H2, CO

Sample Preparation (Easy) Continuous Flow IRMS Simply means that a carrier gas (He) pushes the sample gases into the IRMS. (high throughput, lower precision) Combustion-Reduction (EA-IRMS) CHNOS ==> CO2 + N2 + SO2 1000°C O2 13C 15N organic 34S Carbonate (CaCO3) ==> CO2 13C H3O4P Acid 18O Acidification (GasBench-IRMS) inorganic biogenic

d13C, d15N, d34S via EA-IRMS CHNOS ==> CO2 + N2 + SO2 Time 15Nref 15N 13C 13Cref Autosampler O2 Helium CO2 N2 Water Removal IRMS Flash Combustion (1000°C) CO2 N2 H2O CO2 N2 H2O NOx O2 SO2 Gas Chromatograph Open Split Interface O2 low flow because is not measured + Helium (carrier) Reduction from NOx to N Water removal from combustion CO2 N2 H2O NOx O2 Combustion Reactor Reduction Reactor CO2 N2 CHNOS ==> CO2 + N2 + SO2 1000°C O2 13C 15N 34S

Sample Preparation (Hard) Continuous Flow IRMS Simply means that a carrier gas pushes the sample gases to the IRMS. (high throughput, lower precision) Carbon–Hydrogen Reduction (TCEA-IRMS) organic inorganic CHNO ==> CO + H2 1400 °C 18O 2H carbon Pyrolysis! (combustion without O2) Oxygen–Hydrogen Reduction (TCEA-IRMS) Water ==> CO + H2 1400 °C carbon 18O 2H

d2H, d18O via TCEA-IRMS CHNO ==> CO + H2 Autosampler Time Helium 2Href 2H 18O 18Oref Autosampler Helium Dell ($^&%) CO H2 IRMS Carbon Reduction (≈1400 °C) Gas Chromatograph Open Split Interface Glass column: Pyrolisis – oxygen free carbon reducing environment GC: separates H and CO H2 CO CHNO ==> CO + H2 1400 °C 18O 2H carbon