This table was reviewed on 22 November 2022 and refers to EffecTech’s ISO 17034 scope (Issue No. 004) for Certified Reference Materials and ISO 17025 scope (Issue No. 057) for Calibrated Gas Mixtures.

Certified Reference Materials (CRMs)

All CRM mixtures are issued with a ISO 17034 certificate and an ISO 17025 certificate. To find out why, see our page on calibration gas certificates.

Componentrangecalibration and measurement capability (CMC)*
amount fraction (% mol/mol)amount fraction (% mol/mol)
hydrogen0.05 to 10.3 % relative + 0.001
oxygen0.05 to 30.4 % relative + 0.002
nitrogen0.5 to 200.25 % relative + 0.01
carbon dioxide0.5 to 150.2 % relative +0.002
methane51 to 980.17 – 0.15 % relative
ethane0.5 to 50.25 % relative + 0.001
propane0.2 to 2.50.25 % relative + 0.001
iso-butane0.05 to 0.15
0.15 to 1		0.00045
0.3% relative
n-butane0.05 to 0.15
0.15 to 1		0.00045
0.3% relative
* The calibration and measurement capability is based on a standard uncertainty multiplied by a coverage factor k=2, providing a level of confidence of approximately 95%. The uncertainty evaluation has been carried out in accordance with UKAS requirements