Calibration standards used for breath13CO2 analysis
| Working standard | Certified material | ||||
|---|---|---|---|---|---|
| Type | δ13CPDB(‰) | Type | δ13CPDB(‰) | ||
| 4.5 SQ | −2.673 | Polyethylene foil | −31.83 | ||
| Linde CO2 | −47.41 | Carbonate | −1.45 | ||
| Air gouze B50–404 | −42.50 | Urea | −36.46 | ||
| 5% CO2 in N2 | +0.44 | 5% CO2 in air mix | −30.00 | ||
| Cryo cleaned CO2 | −30.62 | CO2 from Europa | −37.22 | ||
| 5% CO2 in N2 | −29.1 | NBS-19 | +1.87 | ||
| Breath | ≅−25.50 | NBS-20 | −1.06 | ||
| CO299.999% | −32.1560 | NBS 18 | −5.04 | ||