Sulphur species
Depending on the nature of the substrate, the anaerobic digestion process produces sulphur-containing compounds ranging from ppb levels to several thousands of ppm. NPL offers traceable reference standards of binary and multi-component sulphur compounds within biogas. UKAS accreditation is available for matrices of methane and nitrogen.
Component
|
Amount fraction range (µmol/mol)
|
Relative Uncertainty (%)
|
Matrix
|
| Hydrogen sulphide |
0.4 to 5000 |
2 - 5 |
Biogas, Methane or Nitrogen​
|
| Carbonyl sulphide |
0.4 to 5000 |
2 - 5 |
| Carbon disulphide |
0.4 to 200 |
2 - 5 |
| Dimethyl sulphide |
0.4 to 200 |
2 - 5 |
| Ethyl methyl sulphide |
0.4 to 200 |
2 - 5 |
| Diethyl sulphide |
0.4 to 200 |
2 - 5 |
| Methanethiol |
0.4 to 200 |
2 - 5 |
| Ethanethiol |
0.4 to 200 |
2 - 5 |
| 2-propanethiol |
0.4 to 200 |
2 - 5 |
| 1-propanethiol |
0.4 to 200 |
2 - 5 |
| 2-methyl-2-propanethiol |
0.4 to 200 |
2 - 5 |
| Tetrahydrothiophene |
0.4 to 200 |
2 - 5 |
Terpenes
Terpenes are a common impurity found within biogas due to the nature of the biological source material. The presence of trace level terpenes within biomethane cause the scent of typical sulphur odorant additives to be masked, posing a health and safety risk. In addition they are capable of causing degradation of polymeric seal materials used within transmission grid pipelines. NPL provides reference standards containing terpenes within biogas, methane and nitrogen matrices.
Component
|
Amount fraction range (µmol/mol)
|
Relative Uncertainty (%)
|
Matrix
|
| (+/-)-α-pinene |
0.01-10 |
2 - 5 |
Biogas, Methane or Nitrogen​
|
| (+/-)-β-pinene |
0.01-10 |
2 - 5 |
| (+)-3-carene |
0.01-10 |
2 - 5 |
| 1,8-cineole (eucalyptol) |
0.01-10 |
2 - 5 |
| Limonene |
0.01-10 |
2 - 5 |
| Isoprene |
0.01-10 |
2 - 5 |
BTEX
Benzene, toluene, ethylbenzene and xylenes are volatile mono-aromatic hydrocarbons found within biogas. NPL provides reference standards containing terpenes within biogas, methane and nitrogen matrices.
Component
|
Amount fraction range (nmol/mol)
|
Relative Uncertainty (%)
|
Matrix
|
| Benzene |
500 - 2000 |
2 - 5 |
Biogas, Methane or Nitrogen
|
| Toluene |
500 - 2000 |
2 - 5 |
| Ethylbenzene |
500 - 2000 |
2 - 5 |
| m+p-xylene |
500 - 2000 |
2 - 5 |
| o-xylene |
500 - 2000 |
2 - 5 |
Ammonia
Ammonia is produced during the anaerobic digestion process and is found within biogas. NPL provides reference standards containing ammonia within biogas, methane and nitrogen matrices.
Component
|
Amount fraction range (nmol/mol)
|
Relative Uncertainty (%)
|
Matrix
|
| Ammonia |
10 - 1000 |
5 - 10 |
Biogas, Methane or Nitrogen​
|
Biomethane purity testing
NPL offers biomethane purity testing services against our traceable primary reference materials. Please contact us for more information using the option at the bottom of the page.
Proficiency testing
NPL offers ‘on-demand’ proficiency testing schemes for biogas and biomethane composition and impurities. Please contact us for more information using the option at the bottom of the page.
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