1. 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

2. 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

3. 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

4. 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

5. 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