BIPM Key Comparison Research Articles

On-site comparison of Quantum Hall Effect resistance standards of the NMC A*STAR and the BIPM: Ongoing key comparison BIPM.EM-K12

Main textThe ongoing on-site comparison BIPM.EM-K12 is part of the BIPM programme implemented to verify the international coherence of the primary resistance standards. It allows National Metrology Institutes (NMIs) to validate their implementations of the Quantum Hall Effect (QHE) for dc resistance traceability by comparison to the reference maintained at the BIPM.The realization of the ohm from the QHE-based standard of the NMIs at 100 Ω is compared with that realized by the BIPM from its own transportable quantum Hall resistance standard. This comparison is usually completed by scaling measurements from 100 Ω to 1 Ω and 10 kΩ through the measurement of the resistance ratios 100 Ω/1 Ω and 10 kΩ/100 Ω, respectively.In March 2019, a new BIPM.EM-K12 on-site comparison was carried out at the National Metrology Centre, NMC A*STAR (Singapore). It was the first time the NMC A*STAR participated in this comparison programme. Only the measurement results of the 100 Ω based on the quantum Hall effect and of the 10 kΩ/100 Ω ratio are presented in the report. The reason why the results of the 100 Ω/1 Ω ratio were not included is explained in the introduction of the report.Measurements of the 100 Ω transfer standard in terms of the SI value of the von Klitzing constant, R K, agreed to 1.6 parts in 109 with a relative combined standard uncertainty u c = 3.3 × 10−9. Measurements of 10 kΩ/100 Ω ratio agreed to 2.0 parts in 109 with u c = 2.8 × 10−9.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 CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Calibration of diameter standards (EURAMET.L-K4.2015)

Main textAt its meeting in October 2014, the EURAMET TC for Length, decided upon a key comparison on the calibration of diameter gauges, named EURAMET.L-K4.2015. Twenty National Metrology Institutes and one Designated Institute from Europe, Asia and South America participated in this comparison, which was carried out in two parallel groups. Twelve laboratories from EURAMET participated in group 1, while ten laboratories from EURAMET and two laboratories from GULFMET and SIM participated in group 2. To provide the link three laboratories, CEM, INRIM and METAS, participated in both groups and in the key comparison CCL-K4.2015. Two sets of gauges consisting of two rings, two plugs and a sphere were circulated in parallel in the two groups, the circulation started in November 2016 and completed in February 2018. The reference value (KCRV) was calculated on a gauge-per-gauge basis as the weighted mean of the submitted results of the diameter, roundness and straightness measurements. With group 1, inconsistent results (En> 1) gave a number of 5 out of 60 independent results for diameter and 7 out of 77 for roundness, while with group 2 a number of 6 out of 59 for diameter. These numbers are reflected in the comparison with reference values, while it is worth noting that with the two plugs of 100 mm diameter a decrement of 2 inconsistent results is achieved by introducing an uncertainty contribution related to the apparent change of length of these gauges. Furthermore, the KCRV was calculated by linking the two groups for the diameter of all the twin gauges and for the roundness of the twin spheres. When compared to those calculated independently for each group, minor changes of the KCRVs and associated uncertainties are observed from linking the groups. Consistency checks are satisfied for most of the gauges with the exception of the plugs 100 mm, which suffer from an apparent change in length during the circulation. With the linking, inconsistent results gave a number of 12 out of 119 independent results for the diameter and 1 out of 21 for roundness of the sphere. The comparison results help to support the calibration and measurement capabilities (CMCs) of the laboratories, while recommendations and actions were agreed with those having inconsistent results.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).

Report of the CCQM-K152. Assay of potassium iodate

Main textThe CCQM-K152 key comparison in parallel with CCQM-P192 pilot comparison were organised jointly by the Inorganic Analysis (IAWG) and Electrochemical Analysis and Classical Chemical methods (EAWG) working groups of CCQM to test the abilities of the metrology institutes to measure the amount content of the non-metallic elements in high purity salts as well as assaying high purity salts to be used as primary standards.Eight NMIs participated in the key comparison CCQM-K152. Ural Research Institute for Metrology (UNIIM) (since 2020 it has been called Affiliated Branch of D.I.Mendeleev Institute for Metrology (VNIIM-UNIIM)), Russian Federation, acted as the coordinating laboratory of the comparison. There were two measurands: the amount content of oxidants expressed as potassium iodate, mol/kg, and the mass fraction of iodine, kg/kg. The measurement methods used by participants for the amount content of oxidants expressed as potassium iodate were constant current coulometry and titrimetry. For the mass fraction of iodine results were provided by 5 NMIs, 3 of them used the direct approach (recalculation from coulometric or titrimetric results) and 2 NMIs implemented the indirect approach based on impurities assessment using combination of the instrumental methods (ion chromatography, ICP OES, ICP MS).In general, good overlap of results was observed for both measurands. Direct and indirect approaches for purity determination of pure salt provide overlapping results when impurities are summarized in ionic form. The suitability of coulometry for assay of high purity materials was demonstrated again, and some possible technical problems were highlighted.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 kcdb.bipm.org/.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 on APMP.QM-K18.2016 key comparison on pH measurement of carbonate buffer

Main textThis key comparison is being performed to evaluate the degree of equivalence of measurement procedures to support the participants' claims of Calibration and Measurement Capabilities (CMCs) and to evaluate the capabilities of participants for the determination of the pH of carbonate buffer solutions.This is the fourth APMP key comparison on pH measurement following APMP.QM-K9/P16 (phosphate), APMP.QM-K19/P25 (borate) and APMP.QM-K91/P29 (phthalate).The results have the linkage to CCQM-K18.2016 (carbonate buffer) and were evaluated by comparing the results of the Physikalisch-Technische Bundesanstalt (PTB) and the National Metrology Institute of Japan (NMIJ) performing Harned cell method. The results of PTB and NMIJ were used for the definition of the Key Comparison Reference Value (KCRV). The ensuing pH value was calculated based on the Bates-Guggenheim convention to compare the results of primary and secondary methods.In this comparison measurements of pH were performed only at the temperature of 25 °C.The results demonstrated by most participants are in better agreement than those in CCQM-K18.2016.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 kcdb.bipm.org/.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).

Assay of potassium hydrogen phthalate

Main textThe CCQM-K34.2016.1 was organized as a subsequent key comparison of CCQM-K34.2016 assay of potassium hydrogen phthalate to demonstrate the improved capability of the laboratories which did not perform well in the original CCQM-K34.2016. The key comparisons were organized jointly by the working groups of inorganic analysis and electrochemistry analysis. National Institute of Metrology P. R. China (NIM) acted as the coordinating laboratory, and NIM and SMU (Slovak Institute of Metrology) served as linking laboratories to link to the CCQM-K34.2016 key comparison reference value (KCRV). CENAM, NIST and VNIIFTRI registered in K34.2016.1, however, VNIIFTRI gave up participating in the comparison due to failure to get the samples through the customs clearance in Russia. All participants used constant current coulometry for measurement, and improved capabilities were demonstrated.The scope is same as in CCQM-K34.2016. The comparison tested the capabilities and methods used for assay of high purity materials. Good result indicates good performance in assaying the purity （amount content）of solid weak acids.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 kcdb.bipm.org/.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).

CCQM-K143 comparison of copper calibration solutions prepared by NMIs/DIs

Main textCCQM-K143 is a key comparison that assesses participants' ability to prepare single element calibration solutions. Preparing calibration solutions properly is the cornerstone of establishing a traceability link to the International System of Units (SI), and therefore should be tested in order to confirm the validity of CCQM comparisons of more complex materials. CCQM-K143 consisted of participants each preparing a single copper calibration solution at 10 g/kg copper mass fraction and shipping 10 bottled aliquots of that solution to the coordinating laboratory, the National Institute of Standards and Technology (NIST). The masses and mass fraction for the prepared solutions were documented with the submitted samples.The solutions prepared by all participants were measured at NIST by high performance inductively coupled plasma optical emission spectroscopy (HP-ICP-OES). The intensity measurements for copper were not mapped onto values of mass fraction via calibration. Instead, ratios were computed between the measurements for copper and simultaneous measurements for manganese, the internal standard, and all subsequent data reductions, including the computation of the KCRV and the degrees of equivalence, were based on these ratios. Other than for two participants whose measurement results appeared to suffer from calculation or preparation errors, all unilateral degrees of equivalence showed that the measured values did not differ significantly from the KCRV. These results were confirmed by a second set of ICP-OES measurements performed by the Physikalisch-Technische Bundesanstalt (PTB). CCQM-K143 showed that participants are capable of preparing calibration solutions starting from high purity, assayed copper metal. Similar steps are involved when preparing solutions for other elements, so it seems safe to infer that similar capabilities should prevail when preparing many different, single-element solutions.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 kcdb.bipm.org/.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).

Key Comparison CCQM-K73.2018 Amount Content of H+ in Hydrochloric Acid (0.1 mol·kg−1)

Main textThe CCQM key comparison K73.2018 is a follow-up comparison of CCQM-K73. It was performed to demonstrate the capability of the participating institutes to measure the amount content of H+ in hydrochloric acid of 0.1 mol·kg−1 molality. 16 NMIs participated in this comparison. The comparison was coordinated by PTB. The sample showed a slight but significant instability by loss of water of around 0.11 μmol kg−1d−1 corresponding to 0.02 % over the measurement period. Therefore, the results were corrected for this instability. The results of this key comparison show good equivalence between the majority of participants. The equivalence is significantly better compared to the first comparison CCQM-K73.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 kcdb.bipm.org/.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).

Supplementary comparison EURAMET.EM-S42, comparison of lightning impulse (LI) reference measuring systems

Main textIn 2016 the Consultative Committee for Electricity and Magnetism (CCEM) commissioned a supplementary comparison EURAMET.EM-S42 of Lightning Impulse (LI) measurement systems. This comparison was piloted by RISE (Sweden, formerly SP), and it was supported by VTT MIKES (Finland) and FFII LCOE (Spain). Eleven National Metrology Institutes (NMI) and two Designated Institutes (DI) from four Regional Metrology Organizations, EURAMET, COOMET, APMP and SIM, took part in the comparison.A commercial travelling measuring system (TRMS) for Lightning Impulse (LI) measurement was adopted for the comparison. The TRMS consisted of a 700 kV resistive voltage divider and a transient recorder with computer. The TRMS was calibrated by the pilot lab in November 2016 before start of the comparison, and the first circulation was between five EURAMET NMI/DIs. After an intermediate calibration by the pilot lab in July 2017, the TRMS was circulated between seven NMI/DIs in the other regional organisations. On the return of the TRMS in March 2019 a final calibration was made by the pilot lab.The measured parameters are defined in IEC60060-1. Test voltage value (U t), front time (T 1), time to half value (T 2) and relative overshoot (β') were measured for full impulses; and extreme value (U e) and time to chopping (T c) for front chopped waveform. The test voltage value ranged from -700 kV to 700 kV with two full and one chopped impulse waveform. A set of preferred voltage levels and waveforms was defined. The obtained expanded uncertainties (k = 2) of the comparison reference values (CRV) were: <0.3% for U t, <1.3% for T 1, <1.0% for T 2, <0.4% for β', <0.6% for U e and <1.4% for T c.The transfer reference measuring system of the previous LI comparison (EU-SMT4-CT98-2270), arranged between 1999 and 2002, is linked to this comparison. The link is established by comparing VTT MIKES system used 20 years ago with that used in this comparison.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 kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Electrolytic conductivity at pure water level

Main textElectrolytic conductivity in aqueous solutions is a common electrochemical measurement technique in industry. Since it is sensitive to the amount content of dissolved ions in a solution, a limiting value for conductivity is a clear and simple quality criterium for the ionic purity of pure water, roughly ranging from 0.055 μS/cm to 150 μS/cm at 25 °C. International regulations are becoming stricter with regards to metrological traceability to guarantee compliance of measurement results with relevant standards. Consequently, the NMIs active in this area have been facing an increasing request for the calibration of respective conductivity sensors and for adequate CRMs over the past years. A first, regional comparison has been conducted in 2013/14 (EURAMET 1271). Since an increasing number of NMIs, also from other regions, seek providing respective services and establishing CMCs, EURAMET, i.e. the Sub-Committee on Electro Analysis of TC-MC, opened a follow-up comparison to other regions in terms of a supplementary CCQM comparison (EURAMET.QM-S12). The comparison has been conducted in terms of a Round Robin scheme. A conductivity sensor has been sent around between ten participants for calibration at four conductivity levels (0.055, 0.5, 5 and 50 μS/cm at 25 °C). Basically, the measured measurement errors of the device have been compared in terms of conductivity. Additionally, the cell constants calculated from the calibration results have been compared. Apart from very few outliers, the comparison has demonstrated good equivalence of the calibration capabilities.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 kcdb.bipm.org/.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 on GULFMET supplementary comparison of AC energy (GULFMET.EM-S5.1)

Main textA bilateral supplementary comparison for standards of electrical energy has taken place within the framework of GULFMET. The comparison, piloted by State Enterprise 'Ukrmetrteststandard' - UMTS (Ukraine), has involved two laboratories (UMTS and QCC EMI, United Arab Emirates) from regional metrological organizations GULFMET and COOMET. The results presented in this report provides confidence in maintaining traceability for active energy and reactive energy for 1.0, 0.5 Lag, 0.5 Lead power factors at frequencies of 50 Hz and 53 Hz.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 kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Key comparison BIPM.RI(I)-K9 of the absorbed dose to water standards of the LNE-LNHB, France, and the BIPM in medium-energy x-rays

A key comparison has been made between the absorbed dose to water standards of the LNE-LNHB, France, and the BIPM in the medium-energy x-ray range. The results show the standards to be in general agreement at the level of the expanded (k = 2) uncertainty of the comparison of 2 parts in 102. The results are presented in terms of degrees of equivalence for entry in the BIPM key comparison database.Main textTo 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 kcdb.bipm.org/.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).

Bilateral comparison of 1 Ω and 10 kΩ standards (ongoing BIPM key comparisons BIPM.EM-K13.a and 13.b) between the NMC A*STAR (Singapore) and the BIPM

This report gives the result of a bilateral comparison of resistance between the NMC A*STAR (Singapore) and the BIPM carried out in 2018-2019. Two 1 Ω and two 10 kΩ travelling standards belonging to the BIPM were used. The comparison was carried out with an 'A-B-A' pattern of measurements; the standards were measured first at the BIPM for a period of about two months, then for a period of about one month at the NMC A*STAR, and finally again at the BIPM. The measurand was the 4 terminal dc resistance at low power. The BIPM was the pilot laboratory, and the comparison forms part of the ongoing BIPM key comparisons BIPM.EM-K13.a (for 1 Ω) and BIPM.EM-K13b (for 10 kΩ).The results from the NMC A*STAR and the BIPM were found to be in good agreement, with a difference smaller than the relative expanded uncertainty (95% confidence, k = 2) of 0.064 × 10−6 for 1 Ω and 0.036 × 10−6 for 10 kΩ.Main textTo 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 kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Key comparison BIPM.RI(I)-K3 of the air-kerma standards of the LNE-LNHB, France, and the BIPM in medium-energy x-rays

A key comparison has been made between the air-kerma standards of the LNE-LNHB, France, and the BIPM in the medium-energy x-ray range. The results show the standards to be in agreement at the level of the standard uncertainty of the comparison of 3.8 parts in 103. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database.Main textTo 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 kcdb.bipm.org/.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).

EURAMET key comparison 1031 (EURAMET.M.D-K1.1)—solid density comparison

The results are presented of the key comparison EURAMET 1031 (EURAMET.M.D-K1.1) that covered the measurements of density and volume of silicon spheres of three different masses at 20 °C and 101325 Pa. The volume and density determinations of 15 national metrology institutes (NMIs) were checked and linked to the CCM.D-K1 key comparison. The measurements were carried out near 20 °C and at atmospheric pressure by the hydrostatic method in the time interval from 16 May 2008 to 18 Jan 2011.The comparison was performed in two petals with three spheres in each petal. The travelling standards of petal 1 have a mass of 1001 g, 200 g and 35 g (Petal 2: 984 g, 239 g, 35 g). Whereas the reference values of the 1 kg travelling standards could be determined by the link to the CCM.D-K1 comparison, the density reference values for the smaller spheres were determined by density comparison to the 1 kg spheres using the pressure-of-flotation method.One result was wrong due to a mistake in the mass determination. Additionally, four of the 57 volume (or density) values were discrepant with En values larger than 1.1, 1.2, 1.3 and 1.6.Five NMIs achieved density uncertainties of about 1 ppm (1 × 10−6 in relative terms) or less for the 1 kg spheres. This satisfies the needs of all customers who wish to calibrate solid density standards for other laboratories.Volume determinations of mass standards, air density artefacts or sorption artefacts should reach an uncertainty of about 1 mm3 in order to reduce the effect on the mass uncertainty to about 1 μg. At least for silicon spheres this is reached by eight NMIs. Due to the higher density of stainless steel this may be different for weights and will be checked within the CCM.D-K3 comparison.The results of the comparison can be used to submit new or improved entries in the calibration measurement capabilities table in the BIPM key comparison database.Main textTo 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 kcdb.bipm.org/.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).

Bilateral comparison of 10 pF and 100 pF standards (ongoing BIPM key comparisons BIPM.EM-K14.a and 14.b) between the SASO (Saudi Arabia) and the BIPM

This report presents the results of a bilateral comparison between the SASO, Saudi Arabia, and the BIPM, which was carried out using two 10 pF and two 100 pF travelling standards belonging to the BIPM following an "A-B-A" pattern. The comparison at 10 pF forms part of the ongoing BIPM key comparison BIPM.EM-K14.a and that at 100 pF of the ongoing BIPM key comparison BIPM.EM-K14.b, where BIPM is the pilot laboratory for both comparisons.The standards were measured during a total time of 21 weeks, from October 2019 to February 2020. The measurand of this comparison was the two terminal-pair capacitance of the travelling capacitors at a frequency of 1000 Hz, and a measuring rms voltage of 10 V.The results from the SASO and the BIPM agree within a difference smaller than the relative expanded uncertainty of the comparison, which is dominated by the contribution of the calibration of the SASO reference capacitors.Main textTo 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 kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Key comparison BIPM.RI(I)-K7 of the air-kerma standards of the NIM, China and the BIPM in mammography x-rays

A first key comparison has been made between the air-kerma standards of the NIM, Republic of China and the BIPM in mammography x-ray beams. The results show the standards to be in agreement at the level of the combined standard uncertainty of 2.8 parts in 103. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database.Main textTo 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 kcdb.bipm.org/.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)-K7 of the air-kerma standards of the NRC, Canada and the BIPM in mammography x-rays

A key comparison has been made between the air-kerma standards of the NRC and the BIPM in mammography x ray beams. The results show the standards to be in agreement at the level of the combined standard uncertainty of 3.2 parts in 103. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database.Main textTo 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 kcdb.bipm.org/.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).

BIPM comparison BIPM.RI(II)-K1.Ge-68 of activity measurements of the radionuclide 68Ge for the LNMRI/IRD, NIST, NIM, IRA-METAS, LNE-LNHB and the TAEK, and the linked 2015 CCRI(II)-K2.Ge-68 comparison

This report summarises the results for the new BIPM.RI(II)-K1.Ge-68 comparison. Six metrology institutes have participated, enabling the first value of the key comparison reference value(KCRV) to be determined. The KCRV was calculated using the power-moderated weighted mean and the results. A link has been made to the CCRI(II)-K2.Ge-68 comparison held in 2015 through the NIST, NIM,IRA-METAS and the LNE-LNHB who participated in both comparisons. One NMI used the K2 comparison to update their degree of equivalence. The degrees of equivalence between each equivalent activity measured in the International Reference System (SIR) and the KCRV have been calculated and the results are given in the form of a table for the remaining five NMIs in the BIPM.RI(II)-K1.Ge-68 comparison and the 12 other participants in the CCRI(II)-K2.Ge-68 comparison. A graphical presentation is also given.Main textTo 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 kcdb.bipm.org/.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).

Report on the CCM key comparison of kilogram realizations CCM.M-K8.2019

This report describes the first 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 first "consensus value" of the kilogram. The consensus value will serve as the basis for an internationally coordinated dissemination of the kilogram which will continue until sufficient agreement between realization experiments has been achieved.The comparison was organized by the BIPM and had seven participants. The BIPM, KRISS, NIST and NRC 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. The standards were sent (in air) to the BIPM where they were compared under vacuum with each other and with BIPM Pt-Ir working standards. The latter were calibrated (in air) 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 mass standards of 1 kg using the participating realization experiments. 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 can also be deduced.Main textTo 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 kcdb.bipm.org/.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 of the CCQM-K145: toxic and essential elements in bovine liver

Liver plays a major role in metabolism and acts as a source of energy for the body by storing glycogen. With the growing interest and investigation in the biological effects in recent years, it is important and necessary to develop accurate and comparable analytical methods for elements in bio-samples. It has, however, been 10 years since the tissue sample (bovine liver) of CCQM-K49 key comparison. The purpose of CCQM-K145 is to ensure the comparable and traceable measurement results for essential and toxic elements such as P, S, Zn, Mn, Ni, Mo, Sr, Cr, Co, Pb, As and Hg in bovine liver among NMIs and other designated measurement bodies worldwide. The comparison was agreed by IAWG as 6th IAWG Benchmarking Exercise with Zn and Ni as exemplary elements at the meeting in Korea in the early October 2016. The results of CCQM-K145 are expected to cover the measurement capability and support CMCs claiming for inorganic elements in the similar biological tissue materials and food samples.30 NMIs and DIs registered in CCQM-K145. With respect to the methodology, a variety of techniques such as IDMS, ICP-OES, ICP-MS(non-ID), AAS and NAA were adopted by the participants. For Zn, Ni, Sr, Pb and Hg measurements, most participants chose ID-ICP-MS method, which showed the better performance in terms of consistency and reliability of the measurement results. In aspect of the traceability for the measurement results in CCQM-K145, most participants used their own (in house) CRMs or other NMI's CRMs to guarantee trace to SI unit. Most participants used similar matrix CRMs for quality control or method validation.Base on different statistic way to calculate the reference mass fraction values and associated uncertainties for each measurand, removal of the suspected extreme values, and discussion at the IAWG meetings, the median values are proposed as the KCRV for Zn, Ni, Mn, Mo, Cr, Pb and Hg; the arithmetic mean values are proposed as the KCRV for P, S, Sr, Co and As. In general, the performances of the majority of CCQM-K145 participants are very good, illustrating their measurement capabilities for Zn, Ni, P, S, Mn, Mo, Sr, Cr, As, Co, Pb and Hg in a complex biological tissue matrix.Bovine liver contains many kinds of nutrients and microelements, it can be regarded as a typical representative material of biological tissue and food. In CCQM-K145, the analytes involved alkali metals and transition elements, metalloids / semi-metals and non metals with a range of mass fraction from mg/g to μg/kg. CCQM-K145 also tested the ability of NMIs/DIs to determine elements that were easy to be lost and polluted, and interfered significantly. The chemical pretreatment methods of samples used in the comparison is suitable for general food and biological matrix samples. A variety of measurement methods used in the comparison represent the main instrumental technology for elemental analysis. Therefore, for supporting CMC claim, CCQM-K145 is readily applicable to measurement of more elements in a wide range of biological materials (including liquids and solids) and meat products.Main textTo 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 kcdb.bipm.org/.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).