The specific objectives of the project are: To improve the long term stability (2-3 years for static standards) of the measurement standards and the performance of related calibration methods that are used in the measurement of the contents of VOC impurities in biomethane (i.e. the target relative expanded uncertainties are 3 % for total silicon and siloxanes, 3 % for halogenated VOCs, < 4 % for terpenes, and 5 % for amines). To improve the long term stability (2-3 years for static standards) and the performance (i.e., by eliminating biases in the instruments’ readings caused by biomethane, for dynamic standards based on ISO 6145 methods) of the measurement standards and the related calibration methods that are used in the measurement of the contents of corrosive impurities and compressor oil in biomethane (i.e. the target relative expanded uncertainties are 3 % for ammonia, 3 % for HCl, 10 % for HF, 10 % for compressor oil). To develop and validate novel test methods, based on existing calibration methods, for the regular conformity assessment of biomethane during which the content of total silicon and siloxanes, total fluorine and chlorine, ammonia, terpenes, compressor oil, amines, and biogenic methane (based on determining the 14CH4 content in biomethane and blends of biogas and natural gas) are measured. To facilitate the take up of the technology and measurement infrastructure developed in the project by the measurement supply chain (accredited laboratories, instrument manufacturers), standards developing organisations (CEN, ISO) and end users (energy sector, automotive industry). Measurement standards and methods for assessing the particulate content in biomethane and upgraded biogas have already been developed in EMRP JRP ENG54. Progress beyond the state of the art Measurement standards and related novel high-accuracy reference methods for the contents of HF, amines, compressor oil and terpenes currently do not exist for biomethane. In addition, some of the measurement standards for the contents of impurities in biomethane developed in in EMRP JRP ENG54 need further work to be fit for purpose: siloxanes and silicon, halogenated VOCs, ammonia, and HCl. The measurement uncertainty of these standards has been reduced and their long-term stability has been improved and for HCl, the impact of spectroscopic interference on its detection has been reduced, however all still need to be further improved. The preparation of dynamic gas mixtures currently results in a large uncertainty in the development of the measurement standards for ammonia and HCl. The improvements in dynamic gas mixture preparation will improve the state-of-the-art in two ways: a lower expanded uncertainty for the dilution of gas mixtures (down to 1 % – 3 %) and an extension to matrices relevant for the trade in renewable gas (e.g. biomethane). This project will deliver dedicated standardised test methods for the parameters in EN 16723, as well as for terpenes and biogenic methane content, and will disseminate these in the form of a NWIP (New Work Item Proposal) to the working group of ISO/TC 193. These methods replace the currently cited methods in EN 16723, which are not dedicated to biomethane, lack metrological traceability, and have not been demonstrated to be fit-for-purpose. The NWIPs will be accompanied by a summary of the results of the validation and performance evaluation completed by this project, to enable the standardisation committee to assess the suitability of the methods. The method development will use the high-accuracy analytical methods developed in EMRP JRP ENG54 and in this project as their basis and the specificity of the methods will be improved, so that the standardised test methods will generate SI-traceable results with known uncertainty.