This table was reviewed on 19 March 2025 and refers to the following EffecTech scopes of accreditation

• ISO 17025 scope (Issue No. 059) for Primary Reference Materials (PRGMs)
• ISO 17034 scope (Issue No. 006) for Certified Reference Materials (CRMs)

For details of the Expanded Measurement Uncertainty (k = 2) for each component, please check the most recent version of the ISO 17025 scope.

Component	Primary Reference Gas mixtures (amount fraction ppm mol/mol)	Certified Reference Materials (amount fraction ppm mol/mol)
hydrogen sulphide	0.2 to 200	0.2 to 10
carbonyl sulphide	0.2 to 200	0.2 to 10
methanethiol (methyl mercaptan)	0.2 to 200	0.2 to 10
ethanethiol (ethyl mercaptan)	0.2 to 200	0.2 to 10
dimethyl sulphide	0.2 to 200	0.2 to 10
1-propanethiol (n-propyl mercaptan)	N/A	0.2 to 10
2-propanethiol (iso-propyl mercaptan)	0.2 to 200	0.2 to 10
ethyl methyl sulphide (methyl ethyl sulphide)	0.2 to 200	0.2 to 10
1-butanethiol (n-butyl mercaptan)	N/A	0.2 to 10
2-methyl-2-propanethiol (tert-butyl mercaptan)	0.2 to 200	0.2 to 10
2-methyl-1-propanethiol (iso-butyl mercaptan)	N/A	0.2 to 10
1-methyl-1-propanethiol (sec-butyl mercaptan)	N/A	0.2 to 10
diethyl sulphide	0.2 to 200	0.2 to 10
n-hexyl mercaptan	N/A	0.2 to 10
tetrahydrothiophene (THT)	0.2 to 200	0.2 to 10