CIPM Mutual Recognition Arrangement Research Articles

Comparison of standards in field of measurement of 3D parameters of surface texture

Main textIn accordance with the COOMET comparison program for 2019, comparisons of unit length standards in the field of measuring 3D surface texture parameters were carried out in 2019 on the topic COOMET 776/RU-a/19. Pilot laboratory: Russian Research Institute of Metrological Service (VNIIMS, Russia). Participants: Russian Research Institute of Metrological Service (VNIIMS, Russia), Belarussian State Institute of Metrology (BelGIM, Belarus) and KazStandart (Kazakhstan).To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCL, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Calibration of angle standards

Main textOptical polygons and angle gauge blocks are the primary artifacts for disseminating the unit of angle to industry. The Consulative Committee for Length (CCL) has designated the calibration of such angle artifacts as a key comparison topic area in order to ensure world-wide traceability and equivalence of angle measurements at the lowest measurement uncertainties. This report describes the key comparison in the topic area of angle metrology for the SIM region. An optical polygon and six angle gauge blocks were measured by five national metrology institutes (NMI). The comparison was successful and the results of the participants are reported. One NMI reported values that were initially inconsistent with the key comparison reference value for the optical polygon.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCL, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

APMP supplementary international comparison of activity measurement of Cs-134 and Cs-137 in brown rice

Main textThe supplementary international comparison of activity measurement of Cs-134 and Cs-137 in brown rice (APMP.RI(II)-S3.Cs-134.Cs-137) was carried out within the framework of the Asia-Pacific Metrology Programme (APMP). The matrix of the sample was brown rice grain harvested in autumn 2011, after the accident at the Fukushima Daiichi Nuclear Power Plant. No spiking was applied to the sample. Eight institutes reported their measurement results. Averages of the reported results and their associated uncertainties were obtained using the power-moderated mean. This report describes the supplemental comparison reference value, the degree of equivalence of the results, the procedure of the comparison and the sample preparation and measurements by the participants.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

CCT-K7.2021: CIPM key comparison of water-triple-point cells

Main textThis is the final report of CCT-K7.2021 key comparison of water-triple-point (TPW) cells. The primary objective of CCT-K7.2021 was a comparison of the participant national realizations of the TPW temperature. Each participant laboratory selected one of its TPW cells for use as a transfer cell, directly compared it against its national reference and delivered it to the pilot (NRC). The pilot then compared all transfer cells against two NRC reference cells and, finally, each participant laboratory retrieved its transfer cell and directly re-compared it against its TPW national reference. The initial measurements at the participant laboratories were started in April 2021. The final measurements at the participants' laboratories were completed in September 2022. The final report was approved by the CCT WG-KC in April 2023. The adaptive weighted average procedure was adopted to compute the Key Comparison Reference Value (KCRV) and the degrees of equivalence (DoEs) were reported for the participant laboratories. The maximum difference between two transfer cells was 92 μK with a standard deviation of 26 µK (almost a factor of two improvement compared to CCT-K7 results (2002-2004). The maximum difference between two TPW national realizations was 111 µK, with a standard deviation of 28 µK (improvement similar to the one reported for the transfer cells). While the pooled distribution of CCT-K7 results was bimodal, indicating the presence of two different sub-populations (the population of laboratories that referred to ocean water definition and the population of laboratories that did not consider it), the pooled distribution of CCT-K7.2021 results was no longer bimodal, but slightly asymmetrical, indicating a more harmonized approach to water isotopic corrections.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Report on the CCM.T-K2.1 Key Comparison, Measurand Torque: 10 kN∙m and 20 kN∙m, Final Report

Main textThe comparison of torque in the range of 10 kN m and 20 kN m was organized and conducted between two laboratories, the National Metrology Institute of Japan (NMIJ) in the National Institute of Advanced Industrial Science and Technology (AIST) in Japan, and the National Metrology Institute of South Africa (NMISA) in South Africa. This comparison aims to link the national torque standards in South Africa to CCM.T-K2 so that NMISA can achieve the degree of equivalence (DOE) of the CMCs of its torque standards. NMIJ, which had joined CCM.T-K2 key comparison in 2008, played a role of a link laboratory. The results of this comparison showed a good agreement in the NMISA's results with the KCRV.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

CCQM-K68.2019, nitrous oxide (N2O) in air, ambient level, final report

Main textThe key comparison CCQM-K68.2019 was aimed at evaluating the level of comparability of laboratories' capabilities for preparing nitrous oxide in air primary reference mixtures at ambient amount fractions, in the range 320 nmol mol−1 to 350 nmol mol−1.The comparison was coordinated by the BIPM and the KRISS. It consisted in the simultaneous comparison of a suite of 2n primary gas standards, two standards to be prepared by each of the n participating laboratories. Two independent analytical methods were used by the BIPM to analyse the amount fraction of N2O in air, namely Gas Chromatography with an Electron Capture Detector (GC−ECD) and Quantum Cascade Laser Absorption Spectroscopy (QCLAS).Since the circulation of the Draft A report in April 2021, four meetings took place with participants to discuss the mathematical treatment of the comparisons results, and several models were proposed. The model chosen by participants is the Bayesian Errors−In−Variables regression with shades of dark uncertainty. In this final report, the Key Comparison Reference Values were obtained with this model, with calculations performed by B Toman and A Possolo.The key comparison CCQM-K68.2019 is considered to present an analytical challenge and therefore classified as Track C comparison in the CCQM nomenclature.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Update of the BIPM comparison BIPM.RI(II)-K1.Lu-177 of activity measurements of the radionuclide 177Lu to include the 2013 result of the IFIN-HH (Romania), the 2014 result of the LNE-LNHB (France) and the 2022 result of the IRA (Switzerland)

Main text Since 2000, 7 laboratories have submitted 7 samples of 177Lu to the International Reference System (SIR) for activity comparison at the Bureau International des Poids et Mesures (BIPM), with comparison identifier BIPM.RI(II)-K1.Lu-177. Recently, the IFIN-HH (Romania), the LNE-LNHB (France) and the IRA (Switzerland) participated in the comparison. The degrees of equivalence between each equivalent activity measured in the SIR or linked to the SIR from the CCRI(II)-K2.Lu-177 comparison have been calculated. The results are given in the form of a table and a graphical representation is also displayed. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Key comparison BIPM.RI(I)-K4 of the absorbed dose to water standards of the NMIJ, Japan, and the BIPM in 60Co gamma radiation

Main textA new key comparison of the standards for absorbed dose to water of the National Metrology Institute of Japan (NMIJ), Japan, and the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in February 2022. The comparison result, based on the calibration coefficients for two transfer standards and evaluated as a ratio of the NMIJ and the BIPM standards for absorbed dose to water, is 0.9952 with a combined standard uncertainty of 4.0 parts in 103. The result agrees within the uncertainties with the comparison carried out in 2009. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Final report on the CCM key comparison of kilogram realizations CCM.M-K8.2021

Main textThis report describes the second CCM key comparison of realizations of the kilogram definition based on the fixed numerical value of the Planck constant, which came into force on 20 May 2019. The objectives were to determine the level of agreement between realizations of the kilogram using Kibble and joule balances and the x-ray crystal density (XRCD) method and to provide input for the calculation of the second "consensus value" of the kilogram. The consensus value serves as the basis for an internationally coordinated dissemination of the kilogram and is updated after each new key comparison. Its use will continue until satisfactory agreement between realization experiments has been achieved. Another objective was the determination of the reproducibility of the realization experiments by comparing the new results with those of the first key comparison of kilogram realizations, CCM.M-K8.2019.The comparison was organized by the BIPM and had nine participants. The BIPM, LNE, METAS, NIST, NRC and UME operated Kibble balances, the NIM used a joule balance and the NMIJ and the PTB participated using 28Si spheres, the masses of which were determined with the XRCD method. These realization methods were used to calibrate 1 kg mass standards under vacuum or in air. The standards were sent to the BIPM where they were compared with each other and with BIPM Pt-Ir working standards. The latter were calibrated traceable to the International Prototype of the Kilogram (IPK), the mass of which served as the definition of the kilogram until 20 May 2019.The results of the weighings at the BIPM together with the measurement results communicated by the participants allowed comparison of the values attributed to 1 kg mass standards using the realization experiments of the participants. The level of agreement between mass determinations with the realization experiments and the BIPM as-maintained mass unit, traceable to the Planck constant through the mass of the International Prototype of the Kilogram, could also be deduced.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Final report for CCQM-P212: coherence of carbon isotope delta reference materials

Main textThis pilot study evaluates the coherence of carbon isotope delta reference materials (RMs) used by laboratories worldwide. The goal was to assess how well laboratories can realize the VPDB scale using these RMs. In total, carbon isotope delta values of 36 RMs were measured by seven laboratories as well as the vanillin sample previously evaluated in CCQM-K167/P211. A hierarchical Bayesian measurement model was used to evaluate the coherence between these RMs, and to determine the carbon isotope delta value of each of these RMs. In general, this study shows that the 36 carbon isotope delta RMs are reliable. Further, the value assigned to the vanillin sample in this study is within 0.02 ‰ from the CCQM-K167 KCRV.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

EURAMET.T-K.7 Comparison : Inter-laboratory comparison of triple point of water cells

Main textThe purpose of this comparison was to compare the results of the participating laboratories at the triple point of water temperature (TPW) and assess the uncertainty on the practical realization of triple point of water temperature by the participant laboratories and also to support the Calibration and Measurement Capabilities (CMC) entries of the participating laboratories for this fixed point. This comparison was initiated as a EURAMET project with project number 1357. Initially, the participants of the comparison included the Metrology Institutes of Albania (DPM), F.Y.R Macedonia (BOM), Montenegro (MBM) and Serbia (DMDM). But at the later stages of the comparison, these countries understandably chose to leave the comparison instead of repeating the measurements due to an unexpected problem. On the other hand, participants from GULFMET organization, Emirates Metrology Institute (EMI) and National Measurement and Calibration Center at Saudi Standards, Metrology and Quality Organization of the Kingdom of Saudi Arabia (SASO NMCC) and also Jordan National Metrology Institute (JNMI) were included in the comparison after having approvals of each participating laboratory. Then the comparison was registered as Key Comparison with the name EURAMET.T-K7-4 in BIPM KCDB. Finally, two loops was combined together and five institutes performed the comparison with the single circulating TPW Cell. This report presents the results of the TPW comparison and gives detailed information about the measurements made at TUBİTAK UME and participating laboratories.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

RMO SC comparison COOMET.M.H-S3

Main textThis report describes the results of comparison COOMET.M.H-S3. The comparison measurements between the five participants NSC "IM" (pilot laboratory), PTB, CMI, BelGIM, KazInSt were started in December 2014 and ended in December 2016. In the RMO SC, one set of hardness reference blocks was used consisting of 6 (six) blocks of the Superficial-Rockwell scales and hardness levels 90-94 HR15N, 40-50 HR30N, 76-84 HR30N, 43-54 HR45N, 47-53 HR30TW, 70-82 HR30TW. Agreement between the results of the participants is good.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Final report, on-going key comparison BIPM.QM-K1, ozone at ambient level, comparison with NIMT, September 2022

Main textAs part of the ongoing key comparison BIPM.QM-K1, a comparison has been performed between the ozone national standard of Thailand maintained by the National Institute of Metrology (Thailand) (NIMT) and the common reference standard of the key comparison, maintained by the Bureau International des Poids et Mesures (BIPM). The instruments have been compared over a nominal ozone amount fraction range of 0 nmol mol−1 to 500 nmol mol−1.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

High polarity analyte(s) in aqueous media: Determination of L-PFOA and L-PFOS in ground water

Main textTrack C key comparison on determination of L-PFOA and L-PFOS in ground water (CCQM-K156) coordinated by TUBITAK UME was completed in 2022. A subsequent comparison (CCQM-K156.1) was offered to those NMIs or DIs who did not get the chance to participate in the previous comparison or who would like to repeat this measurement challenge.This study provides the means for assessing measurement capabilities for determination of high polarity measurands in a procedure that requires extraction, clean-up, analytical separation and detection. Successful participation in CCQM-K156.1 demonstrates measurement capabilities in determining mass fraction of organic compounds, with molecular mass of 200 g/mol to 700 g/mol, having high polarity pKow > -2, in mass fraction range from 0.5 ng/kg to 500 ng/kg in aqueous media.Five NMIs and DIs participated in CCQM-K156.1 key comparison. SPE was applied in the sample pre-treatment and LC-MS was applied for detection. All participating laboratories applied isotope dilution mass spectrometry (IDMS) techniques for quantification. Participants established the metrological traceability of their results using certified reference materials (CRMs) from NMIs with stated traceability.The CCQM-K156.1 results for L-PFOA and L-PFOS range from 4.71 ng/kg to 9.36 ng/kg with a % RSD of 23.5 % for L-PFOA and from 4.62 ng/kg to 7.67 ng/kg with a % RSD of 18.6 % for L-PFOS. The KCRV and u(KCRV) for this comparison were the results of TUBITAK UME, since TUBITAK UME was a participant in the previous CCQM-K156 and its results agreed well with the CCQM-K156 KCRV. The KCRV was 9.36 ng/kg ± 0.98 ng/kg for L-PFOA and 7.01 ng/kg ± 0.94 ng/kg for L-PFOS. For L-PFOA, the result of SYKE agreed with KCRV, while the results of VNIIM, BAM and NMISA were biased low. As for L-PFOS, BAM, SYKE and NMISA results agreed with the KCRV, whereas VNIIM result was biased low.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Update of the BIPM comparison BIPM.RI(II)-K1.Cs-134 of activity measurements of the radionuclide 134Cs to include the 2014 result of the POLATOM (Poland), the 2014 result of the NRC (Canada), the 2015 result of the LNMRI-IRD (Brazil) and the 2016 result of the PTB (Germany)

Main textSince 1976, 23 laboratories have submitted 44 samples of 134Cs to the International Reference System (SIR) for activity comparison at the Bureau International des Poids et Mesures (BIPM), with comparison identifier BIPM.RI(II)-K1.Cs-134. In the last few years, the POLATOM (Poland), the NRC (Canada), the LNMRI-IRD (Brazil) and the PTB (Germany) participated in the comparison and the key comparison reference value (KCRV) has been updated. The degrees of equivalence between each equivalent activity measured in the SIR or linked to the SIR from the APMP.RI(II)-K2.Cs-134 comparison and the updated KCRV have been calculated and the results are given in the form of a table. A graphical representation is also given.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Final report of CCQM-P225a and b, international comparison on carbon dioxide in air and nitrogen at ambient levels (350 μmol/mol to 800 μmol/mol)

Main textThe pilot studies CCQM-P225a and b aimed at validating the performance of the pVT−CO2 manometric reference facility maintained at the BIPM as a reference for the planned ongoing comparisons BIPM.QM-K2a and b for CO2 in air and nitrogen standards, respectively, over the range 350 μmol mol−1 to 800 μmol mol−1. The planned launch date of the BIPM.QM-K2a and b comparisons is 2024 and will enable NMIs and DIs to have access to on-demand comparisons for their CO2 in air and nitrogen standards over the range 350 μmol mol−1 to 800 μmol mol−1.The pilot studies supplemented the validation activities on the BIPM reference facility already reported in CCQM-P188, and ongoing validation studies against NIST, NOAA and VSL gas standards. A description of the BIPM facility performance will be submitted for publication in a peer-reviewed journal in 2023, with a full uncertainty analysis showing that it can operate with a standard uncertainty of 0.1 μmol mol−1 over the amount fraction range of the comparison (Viallon et al 2023b).The comparison was organised using a sufficient number of independent standards, to demonstrate the performance of the BIPM system, whilst limiting the duration of the pilot study, allowing the key comparison to start as planned in 2024. Following discussions at the 44th GAWG meeting it was decided that comparisons with 3 independent standards at 3 nominal amount fraction values (380, 480 and 800 μmol mol−1) in the two matrices (air and nitrogen) would be sufficient.Results presented in this report show a good agreement between values assigned by participants and those measured at the BIPM, over the entire range of the comparison and for both matrices (air and nitrogen). The BIPM pVT−CO2 facility is ready to act as reference facility for the ongoing key comparison BIPM.QM−K2.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Final report of CCQM-K157 for the measurement of the amount of substance of HfO2 expressed as the thickness of nm films

Main textThe key comparison CCQM-K157 for the thickness measurement of HfO2 films was performed by the Surface Analysis Working Group (SAWG) of the Consultative Committee for Amount of Substance (CCQM). The aim of CCQM-K157 is to establish the measurement traceability and to ensure the equivalency in the measurement capability of national metrology institutes for the thickness measurement of HfO2 films.In this key comparison, the thicknesses of six HfO2 films with the nominal thickness range from 0.7 nm to 6 nm were compared by x-ray photoelectron spectroscopy (XPS), x-ray reflectometry (XRR), transmission electron microscopy (TEM), spectroscopic ellipsometry (SE) and medium energy ion scattering spectrometry (MEIS).To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Report on the AFRIMETS.M.T-S1 supplementary torque comparison for 500 N·m and 1000 N·m between NIS (Egypt) and PTB (Germany)

Main textThe AFRIMETS.M.T-S1 supplementary comparison has been conducted between NIS (Egypt) and PTB (Germany) at the torque of 500 N·m and 1000 N·m in both clockwise and anticlockwise directions. The comparison results revealed the equivalence of torque realized by the 1000 N·m DWTSMs of NIS and of PTB within their measurement uncertainties.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Copper isotope delta measurements in high purity materials: CCQM-P213 pilot study

Main textAccurate and precise isotope ratio measurements of heavy elements are playing an increasingly important role in modern analytical sciences and have numerous applications. Today, isotope ratio measurements are typically performed with two principal techniques: thermal ionization mass spectrometry (TIMS) and multiple collector-inductively coupled plasma mass spectrometry (MC-ICP-MS). To obtain accurate results by mass spectrometry, isotopic certified reference materials (iCRMs) are needed for mass bias correction and for the validation of the method used for analysis. Thus, it is of paramount importance to achieve measurement comparability of all data reported, and to assess measurement capability of each CRM producer/National Metrology Institute (NMI). Therefore, the international comparison (CCQM-P213) was performed to assess the analytical capabilities of NMIs for the accurate determination of copper isotope ratio delta values in high purity materials. The study was proposed by the coordinating laboratories National Research Council Canada (NRC), National Institute of Standards and Technology (NIST), Bundesanstalt für Materialforschung und -prüfung (BAM) and Physikalisch-Technische Bundesanstalt (PTB) as an activity of the Isotope Ratio Working Group (IRWG) of the Consultative Committee for Amount of Substance - Metrology in Chemistry and Biology (CCQM). Participants included six NMIs and one designated institute (DI) from the six countries. Although no measurement method was prescribed by the coordinating laboratories, MC-ICP-MS with either standard-sample bracketing (SSB) or combined SSB with internal normalization (C-SSBIN) models for mass bias correction were recommended. Results obtained from the six NMIs and one DI were in good agreement.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Final report of CCQM-K172 on measurement of Specific Adsorption A [mol/kg] of Ar on zeolite at liquid argon temperature (to enable a traceable determination of the Specific Surface Area by following ISO 9277)

Main textThe CCQM-K172 key comparison on measurement of Specific Adsorption A [mol/kg] of Ar on zeolite at liquid argon temperature (to enable a traceable determination of the Specific Surface Area by following ISO 9277) has been performed by the Surface Analysis Working Group (SAWG) of the Consultative Committee for Amount of Substance (CCQM). The objective of this key comparison is to compare the equivalency of the National Metrology Institutes (NMIs) and Designated Institutes (DIs) for the measurement of specific adsorption of Ar, BET specific surface area) of microporous substances (zeolites, sorbents, ceramics, catalytic agents, etc) used in advanced technology.In this key comparison, a commercial zeolite was supplied as a sample. Five NMIs/DIs participated in this key comparison. All participants used a gas adsorption method, here argon adsorption at 77.3 K, for analysis according to the international standard ISO 9277.In this key comparison, the degrees of equivalence uncertainties for specific adsorption argon, BET specific surface area were established.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).