Gas metrology by calibration-free infrared laser-spectrometry as a potential primary method (Traceable IR laser-spectrometric amount fraction measurements, TILSAM)
Project Description
Laser spectrometry can be used to measure traceable amount of substance fractions of gas species in gas mixtures. A new effort is being planned now within some laboratories of the Gas Analysis Working Group (GAWG) of the CCQM to address spectroscopy as a primary method in gas analysis.
The aim of this EUROMET project is to establish a comparable metrology basis on infrared laser-spectrometry for measurements of amount fractions without calibration procedures.
Key objectives are:
- to develop a protocol for direct-traceable IR laser-spectrometric amount fraction measurements (target date 6/2008)
- to organise a comparison of spectrometric amount fraction measurements based on traceable molecular line strengths for CO2 at levels of 100 - 1000 µmol/mol in N2, the spectrometric results shall be compared to a gravimetric standard (start 1/2009, finalized till 12/2009)
- to agree on a set of molecules and molecular lines to measure traceable line strength data (finalized till 3/2009)
Activities that will be considered will also include the discussion of different laser-spectrometric techniques suitable for the development of spectrometric primary methods. Progress within this project will also be reported to the GAWG of CCQM.
The objectives of the project shall be supported by holding:
- a setup meeting for those EUROMET laboratories interested in the project
- a workshop linked to the activities/progress of the CCQM-GAWG spectroscopy interests to bring together EUROMET laboratories and representatives of communities interested in gas metrology
The results of the project and the comparison will be reported back to METCHEM (interim reports Feb 08 and Feb 09, final report Feb 10).
The setup meeting should be allowed by a discussion on a collaborative research project within the EUROMET EMRP framework
The technical protocal can be downloaded here>>.
Final Report 2011-12-22
The comparison has been finished and the report can be downloaded here>>.
EUROMET Project 934 was the first project in recent gas metrology community's initiative investigating infrared spectroscopy for its use in gas metrology. EURO-934 was a precursor for different following spectroscopy-related project within iMERA-plus and the EMRP.
EURO-934 progressed on the following items:
- A first attempt to establish comparability among EURAMET's gas spectroscopy laboratories was made.
- A technical description of the underlying spectroscopic method was developed, discussed and validated. The respective document on the "TILSAM-method" was made publically available through EURAMET's website as an pdf. This documentary description was used in further EMRP projects to standardize gas spectroscopy.
- Through discussions and date exchange, mainly initiated by the VNIIM collaborator, an online plattform on spectroscopic line fitting was set up.
- A comparison based on two gas mixtures provided by NPL was conducted between DFM and PTB. This comparison proved the TILSAM method applicable to assign amount fraction values to gas mixture species. This comparison was performed measuring carbon dioxide at a 300 and 500 µmol/mol level, respectively, in nitrogen. All but one reported results agreed with the comparison reference value (CRV). The agreeing spectrometric results deviated from the CRV by less than 2 %. Further improvements are possible in order to compete with established analysis methods in gas metrology.
- The final comparison report was made online available on the project's website as a pdf. It's manuscript shall serve as draft for a scientific publication on infrared laser spectroscopy-based carbon dioxide quantification.
- The technical description of the TILSAM method and the comparison report were made online available to trigger further insight and activity amongst EURAMET gas spectroscopy groups, e.g. in the next EMRP calls.