TY - JOUR A1 - Hein, Sebastian A1 - Philipp, Rosemarie A1 - Duewer, D.L. A1 - Gasca-Aragon, H. A1 - Lippa, K. A1 - Toman, B. A1 - Bremser, Wolfram A1 - Calderon, M.A.Á. A1 - Castorena, A.P. A1 - Caixeiro, J.M.R. A1 - Do Rego, E.C.P. A1 - Rosso, A. A1 - De Arechavaleta, R. A1 - O'Connor, G. A1 - Holcombe, G. A1 - Ellison, S.L.R. A1 - Splett, J.D. A1 - Schantz, M.M. A1 - Sharpless, K.E. A1 - Croft, M. A1 - Archer, M. A1 - De Vos, J. A1 - Konopelko, L.A. A1 - Kustikov, Y. T1 - Final report on CCQM-K79: Comparison of value-assigned CRMs and PT materials: Ethanol in aqueous matrix N2 - The 2010 CCQM-K79 'Comparison of value-assigned CRMs and PT materials: Ethanol in aqueous media' is the second key comparison directly testing the chemical measurement services provided to customers by National Metrology Institutes (NMIs) and Designated Institutes (DIs). CCQM-K79 compared the assigned ethanol values of proficiency test (PT) and certified reference materials (CRMs) using measurements made on these materials under repeatability conditions. Nine NMIs submitted 27 CRM or value-assigned PT materials for evaluation. These materials represent many of the higher-order reference materials then available for this commercially and forensically important measurand. The assigned ethanol mass fraction in the materials ranged from 0.1 mg/kg to 334 mg/kg. All materials were stored and prepared according the specifications provided by each NMI. Samples were processed and analyzed under repeatability conditions by one analytical team using a gas chromatography with flame ionization detection (GC-FID) method of demonstrated trueness and precision. Given the number of materials and the time required for each analysis, the majority of the measurements were made in two measurement campaigns ('runs'). Due to a shipping delay from one NMI, an unanticipated third campaign was required. In all three campaigns, replicate analyses (three injections of one preparation separated in time) were made for one randomly selected unit of each of the 27 materials. Nine of the 27 materials were gravimetrically diluted before measurement to provide solutions with ethanol mass fraction in the established linear range of the GC-FID method. The repeatability measurement value for each analyzed solution was estimated as the mean of all replicate values. The within- and between-campaign variance components were estimated using one-way ANOVA. Markov Chain Monte Carlo Bayesian analysis was used to estimate 95% level-of-confidence coverage intervals for the mean values. Uncertainty-weighted generalized distance regression was used to establish the key comparison reference function (KCRF) relating the assigned values to the repeatability measurements. On the basis of leave-one-out cross-validation, all of the assigned values for all 27 materials were deemed equivalent at the 95% level of confidence. These materials were used to define the KCRF. Parametric bootstrap Monte Carlo was used to estimate 95% level-of-confidence coverage intervals for the degrees of equivalence of materials, d ± U95(d), and of the participating NMIs, D ± U95(D). Because of the very wide range of ethanol mass fraction in the materials, these degrees of equivalence are expressed in percent relative form: %d ± U95(%d) and %D ± U95(%D). The median of the absolute values of the %D for the participating NMIs is less than 0.05% with a median U95(%D) of less than 1%. These results demonstrate that the participating NMIs have the ability to correctly value-assign CRMs and proficiency test materials for ethanol in aqueous media and similar measurands. PY - 2013 U6 - https://doi.org/10.1088/0026-1394/50/1A/08005 SN - 0026-1394 SN - 1681-7575 VL - 50 IS - 1A / Technical Suppl. 2013 / 08005 SP - 1 EP - 49 PB - Inst. of Physics Publ. CY - Bristol AN - OPUS4-27730 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Urquiza, M.P. A1 - Torres, M.M. A1 - Mitani, Y. A1 - Schantz, M.M. A1 - Duewer, D.L. A1 - May, W.E. A1 - Parris, R.M. A1 - Wise, S. A. A1 - Kaminski, Katja A1 - Philipp, Rosemarie A1 - Win, Tin A1 - Rosso, A. A1 - Kim, D.H. A1 - Ishikawa, K. A1 - Krylov, A.I. A1 - Kustikov, Y.A. A1 - Baldan, A. T1 - Final report on CCQM-K47: Volatile organic compounds in methanol N2 - KEY COMPARISON At the October 2005 CCQM Organic Analysis Working Group Meeting (IRMM, Belgium), the decision was made to proceed with a Key Comparison study (CCQM-K47) addressing the calibration function for the determination of volatile organic compounds (VOCs) used for water quality monitoring. This was coordinated by CENAM and NIST. Benzene, o-xylene, m-xylene and p-xylene were chosen as representative VOCs. The solvent of choice was methanol. Key Comparison CCQM-K47 demonstrated the capabilities of participating NMIs to identify and measure the four target VOCs in a calibration solution using GC-based methods. The measurement challenges in CCQM-K47, such as avoiding volatility loss, achieving adequate chromatographic resolution and isolating potential interferences, are typical of those required for value-assigning volatile reference materials. Participants achieving comparable measurements for all four VOCs in this Key Comparison should be capable of providing reference materials and measurements for VOCs in solutions when present at concentration levels greater than 10 µg/g. PY - 2013 U6 - https://doi.org/10.1088/0026-1394/50/1A/08021 SN - 0026-1394 SN - 1681-7575 VL - 50 SP - 08021, 1 EP - 24 PB - Inst. of Physics Publ. CY - Bristol AN - OPUS4-31071 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -