COOMET TECHNICAL COMMITTEE 1.8 PHYSICAL CHEMISTRY

Transcription

1 COOMET TECHNICAL COMMITTEE 1.8 PHYSICAL CHEMISTRY CООМЕТ PROJECT 664/RU/14 SUPPLEMENTARY COMPARISON OF STANDARD GAS MIXTURES: «Atmospheric air pollutants: CO in Nitrogen, 5 µmol/mol - Technical Protocol, May Background (CO) presents in atmosphere due to different natural and antropogenic sources. Ambient CO ranges from 50 nmol/mol to 300 nmol/mol at marine boundary and from 100 nmol/mol to 500 nmol/mol at city area. is a toxic gas and in concentrations higher than 3-5 µmol/mol it is hazardous to human health. The first key comparison on carbon monoxide in nitrogen dates back to 1992 year (CCQM- K1a). Gas mixtures of CO in nitrogen are the first types of gas mixtures that were used in international key comparisons. Since then, numerous national metrology institutes (NMIs) have been setting up facilities for gas analysis, and have developed claims for their calibration and measurement capabilities (CMCs) for these mixtures. During past years there were carried out few comparisons on this topic: EUROMET 900a (2007), CCQM-K51 (2009) and COOMET.QM-S3 (2014). The aim of the comparison: Recognition of national measurement standards of national metrological institutes: KazInMetr (Kazakhstan), BelGIM (Belarus) and VNIIM (Russian Federation) and formation of calibration and measurement capabilities (CMC) for the inclusion to the KCDB in accordance with the Mutual Recognition Arrangement (CIPM MRA) for national measurement standards and for calibration and measurement certificates issued by NMIs. 2. Participants: VNIIM, Russia KazInMetr, Kazakhstan BelGIM, Belarus 1

2 3. Subject of the study The subject of the study is gas mixture of СО in nitrogen in cylinders under pressure prepared gravimetrically at the research department for the State measurement standards in the field of physical-chemical measurements of VNIIM. The concentrations of components in gas mixtures lie within the following range: 5 µmol/mol Nitrogen balance The concentration of the target component in the gas mixtures is calculated according to the ISO 6142 from purity analyses and gravimetry, with checking of composition by an analytical procedure. The reference value is assigned to each gas mixture on the base of the gravimetric preparation. Cylinders with volume 5 dm 3 will be used for preparation of СО in nitrogen gas mixtures. The pressure in cylinders before the dispatch to participants will be approximately 7.0 MPa. 4. The task of the participants The participants should determine the value of СО mole fraction in the received gas mixtures. There should be implemented three independent measurements obtained under repeatability conditions. The form of the measurement report is given in Annex 1. Participating laboratories should specify in detail which analytical method was applied, which calibration method was used, as well as the way in which the own calibration samples were prepared. Also the measurement report should contain calculation of the expanded uncertainty and the uncertainty budget. Measurement reports are sent in Word format using . After the measurements, cylinders with gas mixtures have to be returned to coordinating laboratory. Pressure in cylinders, before shipping to coordinating laboratory should be not less than 4,0 MPa, it is necessary for re-analysis in VNIIM. Participants should pay for the return of the cylinders to coordinating laboratory. 5. The responsibility of the coordinator VNIIM, as a coordinator will have to: - register of the comparison in the data base KCDB; 2

3 - prepare and examine samples of gas mixtures in cylinders under pressure; - organize and pay for shipment of the cylinders to participating laboratories; - be responsible for data collecting from participants and for the report developing; - correct the report according to comments of experts; - send preliminary and final reports to participating laboratories; - send the final report to COOMET and BIPM. N пп 6. Time schedule of the comparison Content 1 Preparation of the technical protocol and agreement with May 2015 participants 2 Preparation of gas mixtures in cylinders in the coordinating June 2015 laboratory 3 Stability research of prepared gas mixtures June -July Shipment of the cylinders to participants August Study of the gas mixtures by participants August - September Reports due to the coordinating laboratory October Cylinders due to the coordinating laboratory November Re-analysis of the gas mixtures by the coordinating laboratory December Draft А report February 2016 Coordinator of the key comparison: VNIIM, Leonid Konopelko Phone: Fax: lkonop@b10.vniim.ru Contact persons: VNIIM, Olga Efremova Phone: Fax: VNIIM, Alisa Orshanskaia Phone: Fax: lkonop@b10.vniim.ru lkonop@b10.vniim.ru 3

4 Annex 1 COOMET 664/RU/14 Supplementary comparison of gas mixtures standards: Atmospheric gases-pollutants: CO in nitrogen 5 micmol/mol MEASUREMENT REPORT I. Results of study Laboratory: Cylinder number: Measurement 1 dd/mm/yy Result (mol/mol) Standard deviation (% relative) Number of sub measurements n Measurement 2 dd/mm/yy Result (mol/mol) Standard deviation (% relative) Number of sub measurements n Measurement 3 dd/mm/yy Result (mol/mol) Standard deviation (% relative) Number of sub measurements n Note: Please copy this table as many times as needed for reporting additional measurements 4

5 Final results: Result Assigned expanded Gas mixture (assigned value) Coverage factor uncertainty mol/mol mol/mol II. Description of study Instrument(s) Principles, make, type, configuration, data collection etc. Calibration Standards Calibration Standards for the measurements (preparation method, purity analyses. estimated uncertainty etc.) Instrument Calibration Calibration procedure (mathematical model/calibration curve, number and concentrations of standards, measurement sequence, temperature/pressure correction etc.) Sample Handling How were the cylinders treated after arrival (e.g. stabilized) and how were samples transferred to the instrument? (automatic, high pressure, mass-flow controller, dilution etc) Uncertainty table: Uncertainty Estimate Assumed Standard Sensitivity Contribution to source x i distribution uncertainty coefficient standard X i u(x i ) c i uncertainty u i (y) 5

6 Coverage factor: Expanded uncertainty: Optional You may provide additional data like the raw measurement data, information on your measurement procedure, chromatograms etc. 6