Ensuring measurements are comparable
Traceable, accurate and stable gas reference standards for the most potent greenhouse gases and related components are required to develop our understanding of the increasing influence of human activity on the global atmosphere, address the effects of climate change, and provide the basis for stable and comparable measurements of these gases.
The National Physical Laboratory (NPL) provides SI traceable gas reference materials for amount fraction. Our gas reference materials are supplied in a synthetic air matrix comprising argon, oxygen, and nitrogen at ambient amount fractions. As such, our gas reference materials are suitable for calibrating a range of ambient atmospheric analysers, including cavity ring-down spectrometers, tuneable diode laser absorption spectrometers, mid-infrared absorption spectrometers or gas chromatographs.
We also provide information on the isotope ratio of the gases used to prepare our reference materials and can offer certification of isotope ratio for some gas reference materials in-house. These measurements are traceable to VPDB, VSMOW/SLAP and Air/N2. These reference materials are suitable for calibration of isotopic analysers and are often used for source apportionment of greenhouse gases.
The tables below give an indication of the available mixtures; others may be available on request. Please contact us for more information.
| Gas |
Amount fraction range [μmol mol-1] |
Typical amount fraction uncertainty (k=2) [%] |
Matrix* |
| CO2 |
380 – 800
Other amount fractions may be available on request |
0.2 |
Synthetic air
N2 is available on request |
| CH4 |
1.8 - 2.5
Other amount fractions are available on request |
0.2 |
Synthetic air
N2 is available on request |
|
N2O
|
0.32 - 0.35
Other amount fractions are available on request |
1 |
Synthetic air
N2 is available on request |
| CO |
Available on request |
|
|
| Gas |
Amount fraction range [μmol mol-1] |
Typical amount fraction uncertainty (k=2) [%] |
Matrix* |
Isotopic values available [‰] |
Isotope ratio traceability |
| CO2 |
400 – 420,
800 |
0.2 |
Synthetic air |
δ¹³C: δ¹⁸O:
+ 2 -8
-42 -36
-20 -22
- 9 -15 |
VPDB
VSMOW/SLAP |
| CH4 |
1.8 - 2.5 |
0.2 |
Synthetic air |
δ¹³C: -39 δ²H: -195 |
VPDB VSMOW/SLAP |
|
N2O
|
0.32 - 0.35 |
1 |
Synthetic air |
δ¹⁵NSP δ¹⁵N δ¹⁸O
1 0.2 3
-4 53 103 |
AirN2
VSMOW/SLAP |
*Synthetic air contains Ar, O2 and N2 at ambient amount fractions.
Multicomponent reference materials are available on request. Reference materials are typically provided in a 10 L cylinder BS314 no 14 valves at 100 bar.
Contact us for quotes and enquiries