International key comparison

Iteratioal key compariso COOMET.QM-K76 (COOMET project 484/RU/09) KEY COMPARISON OF PRIMARY STANDARD GAS MIXTURES: SO i Nitroge (100 μmol/mol) Sait-Petersburg 013 1

Fial report L.A. Koopelko 1, Y.A. Kustikov 1, A.V. Kolobova 1, N.B. Shor 1, O.V. Efremova 1, M.S.Rozhov, D.M. Melyk, V.G. Kozia, S.A. Shpilyi, P.V. Petryshy, S.E. Iakubov, A.S. Kluchits 3, V.N. Aayi 3, A.M. Mirochik 3, M.V. Mokhach 3, M. Valkova 4, V. Stovcik 4 1 D.I.Medeleyev Istitute for Metrology (VNIIM), 19, Moskovsky pr., St-Petersburg, 190005, Russia. All Ukraiia State Research-Idustrial Ceter of Stadardizatio, Metrology, Certificatio ad Protectio of Cosumers (Ukrmetrteststadard), 4, Metrologicheskaya str., Kiev, 03143, Ukraie. 3 Belorussia State Istitute for Metrology (BelGIM), Departmet of Physical, Chemical ad Optical measuremets, sector of verificatio gas mixtures ad stadards, 93, Starovilesky trakt, Misk, 0053, Belarus. 4 Slovak Istitute of Metrology (SMU), Karloveska 63, SK-84 55, Bratislava, Slovakia. Field Amout of substace: gas aalysis Subject Key compariso of primary stadard gas mixtures SO i Nitroge (100 μmol/mol). Participats Istitute City Coutry VNIIM Sait-Petersburg Russia Ukrmetrteststadard Kiev Ukraie BelGIM Misk Belarus SMU Bratislava Slovakia Orgaizig body TC 1.8 «Physical Chemistry» COOMET

Backgroud Sulfur dioxide (SO ) is oe of the mai cotamiats occurrig i the atmopshere due to coal, oil ad atural gas burig, base metals smeltig ad sulfuric acid productio. SO has bee the subject of three previous CCQM comparisos: CCQM-K1.d (1997), CCQM- K6b (005) ad CCQM-K76 (010). D.I.Medeleyev Istitute for Metrology (VNIIM) proposed a ew COOMET project 484/RU/09 Key compariso of primary stadard gas mixtures: SO i Nitroge (100 μmol/mol), which was registered i the KCDB BIPM as COOMET.QM-K76. The results of this compariso will be liked with the results of CCQM-K76. Foudatio of the compariso Recogitio of atioal measuremet stadards from Natioal Metrology Istitutes (NMIs) ad eterig of calibratio ad measuremet capabilities (CMCs) ito the Key Compariso Database (KCDB) i accordace with the Mutual Recogitio Arragemet (CIPM MRA) for atioal measuremet stadards ad for calibratio ad measuremet certificates issued by NMIs; Objective of NMIs which participated i comparisos of this type earlier is to support or improve their CMCs. Coduct of the Compariso The gas mixtures for the compariso were prepared gravimetrically i accordace with requiremets of ISO 614 [1] ad were studied regardig their compositio ad stability at the coordiatig laboratory i accordace with requiremets of ISO 6143 []. Gas mixtures for the compariso was prepared from pure substaces by a 3 stage dilutio. The omial amout fractio of the SO mixtures was 100 mol/mol with the actual amout fractio of each beig slightly differet. There were 5 gas mixtures prepared i cyliders ad 4 of them were chose as travelig stadards. The pressure of mixtures i the cyliders was approximately 100 bar; cyliders of 5 liters volume were used. All the mixtures uderwet verificatio prior to shippig to participats by checkig cosistecy withi this set of mixtures ad also with older VNIIM referece stadards. All measuremets were carried out o a UV absorptio spectrometer. After verificatio ad stability testig (stability was cotrolled times durig a period of 3 moth) the prepared cyliders were set to participats. Each participat received oe cylider i February-March 01. All the participatig laboratories carried out measuremets ad submitted reports by September 10, 01. All the travelig stadards were retured to VNIIM by the ed of August 01. The retured cyliders were aalyzed repeatedly i VNIIM to assure that the compoet remaied stable throughout the compariso. Measuremet protocol The measuremet protocol requested each laboratory to perform at least 3 measuremets obtaied uder repeatable coditios icludig at least three separate calibratios. The protocol iformed the participats about the omial amout fractio. The laboratories were also requested to submit a summary of ucertaity evaluatio for the preseted results. 3

Measuremet model The amout of substace fractios obtaied from the gravimetry ad purity aalysis of the paret substaces were used as referece values. The combied stadard ucertaity of a referece value u i,ref (for a mixture i) was calculated o the basis of the followig equatio: u u u u i, ref i,grav i, ver i,stab (1) where u i,grav is the stadard ucertaity of gravimetric preparatio, u i,ver is the stadard ucertaity from verificatio ad u i, stab is the stadard ucertaity cocered with stability. The gravimetric ucertaity is determied by: u u u i, grav i,weighig i,purity () where u i,weighig is the stadard ucertaity of weighig process ad u i,purity is the stadard ucertaity due to the purity of the paret gases. Log-term stability measuremets did ot show ay chage i the amout fractio of the target compoets withi accuracy of these measuremets, so that there was ot ay correctios due to istability. The stadard ucertaity cocered with stability was take as zero u i,stab = 0. The expressio for the combied stadard ucertaity of a referece value becomes thus: u u i u (3) i, ref,grav i, ver Measuremet methods ad calibratio procedures Summary of measuremet ad calibratio methods is show i the table 1. Table 1 Measuremet ad calibratio methods Laboratory Measuremet method Calibratio method VNIIM UV absorptio sigle poit spectroscopy ow stadards Ukrmetrteststadard Fluorescece Liear aalytical fuctio ow stadards BelGIM NDIR Liear aalytical fuctio usig the software B_ Least, ow stadards SMU Fluorescece sigle poit ow stadards Total umber of measuremets 3 measuremets 4- submeasuremets 3 measuremets 10 submeasuremets 3 measuremets 4-3 submeasuremets 3 measuremets 30 submeasuremets 4

Degrees of equivalece The uilateral degree of equivalece D i for each participatig laboratory i the compariso is defied i accordace with the equatio: Di x (4) x i,lab KCRV Sice the compariso gas mixtures had (slightly) differet amout fractios ad takig ito accout the fact, that the pilot laboratory prepared the mixtures usig the same methods ad materials, the idividual values based o gravimetry ad purity aalysis ca be adopted as referece values. Hece the degree of equivalece ca be expressed as: Di x (5) x i,lab i,,ref The combied stadard ucertaity of the degree of equivalece ca be expressed as u( D ) i u i, lab u i,grav ui,ver (6) The expaded ucertaity U D ) at a 95 % cofidece level ( i U( D ) k i u i, lab u i,grav ui,ver (7) Where k is a coverage factor, k= I figure 1, the degrees of equivalece for the participatig laboratories are give relative to the referece value. The ucertaities are, as required by the MRA [3], give at 95 % cofidece itervals. For evaluatig the ucertaity of the degrees of equivalece, the ormal distributio has bee assumed. For obtaiig the stadard ucertaity of the laboratory results, the expaded ucertaity (stated at a cofidece level of 95 %) from the laboratory was divided by the reported coverage factor. 5

Relative deviatio from the referece value, % COOMET.QM-K76- Degrees of equivalece 1,5 1 0,5 0-0,5-1 -1,5 - VNIIM SMU Ukrmetrteststadard BelGIM Figure 1 Degrees of equivalece relative to the referece value, SO i Nitroge (100 μmol/mol) 6

Results I this sectio the results of the compariso are summarized. I the table the followig data is preseted x i,grav u i,grav u i,ver u i,ref x i,lab u i,lab D i amout of substace fractio from gravimetric preparatio, mol/mol stadard ucertaity of x i,grav, mol/mol ucertaity from verificatio, mol/mol ucertaity of the referece value, mol/mol result of laboratory, mol/mol stated stadard ucertaity of laboratory, mol/mol degree of equivalece (differece betwee laboratory result ad referece value), mol/mol U(D i ) expaded ucertaity of D i at 95 % level of cofidece, mol/mol k assiged coverage factor for degree of equivalece D i,rel relative form for degree of equivalece (D i,rel = D i *100/ x i,grav ), % U(D i ) rel relative form for expaded ucertaity of D i (U(D i ) rel = U(D i )*100/ x i,grav ), % Table -Results Laboratory Cylider x i,grav u i,grav u i,ver u i,ref x i,lab u i,lab D i k U(D i ) D i,rel U(D i ) rel VNIIM D48475 100.00 0.047 0.053 0.071 100.10 0.10 0.10 0,.5 0.10 0.5 SMU D48464 100.15 0.047 0.053 0.071 100.31 0.63 0.16 1.3 0.16 1.3 Ukrmetrtestst adard S198746 100.48 0.047 0.053 0.071 100.14 0.50-0.34 1.0-0.34 1.0 BelGIM S198760 100.74 0.047 0.053 0.071 100.14 0.56-0.60 1.1-0.60 1.1 VNIIM ad SMU participated i CCQM K76 compariso Sulfur Dioxide i Nitroge. But the results of SMU showed sigificat deviatio from the referece value (D i,rel =,18 %, U(D i ) rel =1,06 %). VNIIM showed cosistet results i CCQM K76 (D i,rel =0,37 %, U(D i ) rel =0,7 %).VNIIM could be cosidered as likig laboratory to CCQM-K76. 7

Discussio ad coclusios All the results are cosistet with the referece values. The observed differeces betwee the referece ad reported values are withi ±0,60 % relative to the gravimetric values, ad do ot exceed the appropriate assiged expaded ucertaities. VNIIM is the likig laboratory to CCQM-K76. SMU has improved the result obtaied i CCQM-K76. The prepared mixtures were foud to be stable durig about a year withi the ucertaity of the measuremets. Referece [1] Iteratioal Orgaizatio for Stadardizatio, ISO 614:001 Gas aalysis - Preparatio of calibratio gas mixtures - Gravimetric methods, d editio. [] Iteratioal Orgaizatio for Stadardizatio, ISO 6143:001 Gas aalysis Compariso methods for determiig ad checkig the compositio of calibratio gas mixtures. [3] CIPM, Mutual recogitio of atioal measuremet stadards ad of calibratio ad measuremet certificates issued by atioal metrology istitutes, Sevres (F), October 1999 Coordiator Leoid Koopelko 1D.I.Medeleyev Istitute for Metrology (VNIIM), Research Departmet for the State Stadard i the Field of Physical-Chemical Measuremets (PCD), 19, Moskovsky pr., St-Petersburg, 190005, Russia Tel: +7 81 315 11 45 Fax: +7 81 37 97 76 E-mail:lkoop@b10.viim.ru Completio October 013 8

Aex A Reports submitted by participatig laboratories 9

BelGim report COOMET.QM-K76 (COOMET Project No. 484/RU/09) Key compariso of primary stadards gas mixtures: SO i Nitroge (100 μmol/mol) MEASUREMENT REPORT I. Results of study Laboratory: BelGIM Cylider umber: S198760 (5 dm 3 ) Measuremet No. 1 Result (μmol/mol) Stadard deviatio (% relative) Number of sub measuremets Sulfur dioxide 10/04/01 100.15 0.54 4 Measuremet No. Result (μmol/mol) Stadard deviatio (% relative) Number of sub measuremets Sulfur dioxide 13/04/01 100.0 0.55 4 Measuremet No. 3 Result (μmol/mol) Stadard deviatio (% relative) Number of sub measuremets Sulfur dioxide 1/04/01 99.94 0.54 3 Measuremet No. 4 Result (μmol/mol) Stadard deviatio (% relative) Number of sub measuremets Sulfur dioxide 15/05/01 100.44 0.54 4 Fial results: Gas mixture Result (assiged value) μmol/mol Coverage factor Assiged expaded ucertaity μmol/mol Sulfur dioxide 100.14 1.1 10

Istrumet(s) II. Descriptio of study Measuremet priciple: NDIR. Istrumet: Gas aalyzer AO00 with aalyzer module Uras 6 ( ABB, Germay) as a part of the Natioal Stadard (NS RB 18-10). Calibratio stadards Calibratio stadards were prepared by a gravimetric method i accordace with ISO 614. Molar masses of the compoets ad their associated ucertaities were derived from ISO 1491(E). Characteristics of iitial substaces used to prepare calibratio stadards are give i Table 1. Table 1 - Characteristics of iitial compoets Iitial gas SO Mole fractio Stadard ucertaity Compoet mol/mol 10 - mol/mol 10 - SO 99.98 0.01 Iitial gas N Mole fractio Stadard ucertaity Compoet mol/mol 10 - mol/mol 10 - N 99.9999 0.00003 All calibratio stadards were filled ito 10 liter alumium cyliders with ACULIFE IV+III treatmet (Scott Specialty Gases) fitted with stailess steel valves; premixtures were filled ito metal composite cyliders fitted with stailess steel valves. Preparatio was performed i 3 steps: 90 SO μmol/mol 99.98 SO 0.4 SO 0.05 SO mol/mol 10 - mol/mol 10 - mol/mol 10-100 SO μmol/mol 110 SO μmol/mol 3 calibratio stadards were prepared; characteristics thereof are give i Table. Table Characteristics of calibratio stadards No. of Assiged value (x) calibratio Compoet μmol/mol stadard 1 3 Stadard ucertaity (u(x)) μmol/mol SO 90.41 0. N balace SO 100.76 0.5 N balace SO 110.87 0.8 N balace 11

Istrumet calibratio The istrumet was calibrated i accordace with ISO 6143 usig three calibratio stadards metioed above. Parameters of the aalytic fuctio were calculated usig software B_Least. The aalytic fuctio is liear. Measuremet sequece: calibratio stadard (1) sample gas mixture calibratio stadard () sample gas mixture etc. At least three repeated submeasuremets were doe for the sample gas mixture i each measuremet series. Hadlig of sample Before measuremets cyliders with the sample ad with the calibratio stadards were held at room temperature for at least 4 hours. The cyliders had stailess steel flow regulators. The trasfer system to deliver the sample ito the istrumet was made of a fluoroplastic pipe of 5 mm i diameter. The sample was fed ito the istrumet from a overflow by meas of a embedded pump at a flow rate of (35.0±0.3) l/h. Betwee measuremets the trasfer system ad the istrumet were purged with high purity 6.0 Grade itroge. Ucertaity calculatio Ucertaity value u (x) was calculated i accordace with ISO 6143 takig ito accout the ucertaities of the calibratio stadards ad istrumet respose variability durig calibratio ad measuremets uder reproducibility coditios: u( x) u ( x, xcs ) u ( x, y), where u x, x ) - the stadard ucertaity associated with the amout-of-substace fractios of the ( CS calibratio stadards; u( xcs ) i u( x, xcs ), i 1 where u ) - ucertaity of the calibratio stadards; ( x CS i - umber of the calibratio stadards; u ( x, y) - ucertaity associated with the istrumet respose, u( x, y) u ( y) x u ( a1 ) x cov( a0, a1) u a 1 ( a ) 0 where u (y) - ucertaity of istrumet respose durig measuremets; a a, u( a ), u( a ), cov( a, ) - calibratio fuctio parameters obtaied from B_Least for liear 0, 1 0 1 0 a1 fuctio. The calibratio fuctio parameters of all measuremets are give i Table 3. 1

Table 3 - Calibratio fuctio parameters 1 st d 3 rd 4 th Parameter measuremet measuremet measuremet measuremet Regressio coefficiet -1.5939 10 a 5-1.663 10 5-1.5040 10 5-1.495 10 5 0 Regressio coefficiet a 1 Regressio coefficiet a ucertaity u a ) 0 ( 0 Regressio coefficiet a ucertaity u a ) 1 ( 1 3.7784 10 3 3.8391 10 3 3.786 10 3 3.8011 10 3 1.3714 10 4 1.3758 10 4 1.377 10 4 1.3735 10 4 1.3674 10 1.3719 10 1.3687 10 1.3696 10 Covariace cov( a 0, a1) -1.8686 10 6-1.8810 10 6-1.873 10 6-1.8746 10 6 Ucertaity table: Ucertaity source X i Ucertaity associated with the amout-ofsubstace fractios of the calibratio stadards Ucertaity associated with the istrumet respose Estimate x i Assumed distributio Normal Normal Stadard ucertaity u(x i ) 0.15 μmol/mol 0.54 μmol/mol Sesitivity coefficiet c i 1 1 Cotributio to stadard ucertaity u i (y) 0.15 μmol/mol 0.54 μmol/mol Coverage factor: k =. Expeded ucertaity: 1.1 μmol/mol. 13

SMU report COOMET.QM-K76 (COOMET project 484/RU/09) Key compariso of primary stadard gas mixtures: SO i Nitroge (100 μmol/mol) MEASUREMENT REPORT I. Results of study Laboratory: Slovak Istitute of Metrology SMU Cylider umber: D48464 Measuremet 1 Result (μmol/mol) Stadard deviatio (% relative) Number of sub measuremets Sulfur dioxide 5.3.01 100.9 0.5 30 Measuremet Result (μmol/mol) Stadard deviatio (% relative) Number of sub measuremets Sulfur dioxide 18.4.01 100.33 0. 30 Measuremet 3 Result (μmol/mol) Stadard deviatio (% relative) Number of sub measuremets Sulfur dioxide 10.5.01 100.30 0.19 30 Fial results: Gas mixture Result (assiged value) (μmol/mol) Coverage factor Assiged expaded ucertaity (μmol/mol) Sulfur dioxide 100.31 1.6 14

Istrumet(s) II. Descriptio of study The cocetratio of SO was determied by fluorescece method i gas laboratory. Thermo Visio 43C aalyzer was used for measuremets. SO cotet was measured after receivig the cylider from pilot laboratory ad the two times after 3 weeks. 5 out of differet PSMs i the mole fractio rage (10-100) µmol/mol SO were used to make a calibratio curve ad afterwards from calibratio curve were estimated a ukow quatity of assay. Data collectios were doe maually from equipmet by readig 30 sec iterval. Each measuremet was performed uder stable coditios: Pressure: 73.5 mmhg Flow: 0.487 l per mi. Itegratio time: 30 sec The laboratory coditios: Temperature: 0-3 C Pressure: 98.90-101.35 KPa, Rel. humidity: 0%-35%. Calibratio Stadards The calibratio stadards for measuremets (SMU`s PSM) prepared gravimetrically i accordig to ISO 614. 6 out of differet PSM were used for makig liear calibratio curve for SO cotets (1-100 µmol/mol). PSM Sulfur dioxide mole fractio x SO Expaded ucertaity U ) ( x SO Coverage Factor [μmol/mol] [μmol/mol] MY9733_4 0.9069 0.03 MY9734_4 5.54 0.03 MY9738_4 11.19 0.081 MY9735_4 49.76 0.35 MY9737_3 80.01 0.87 MY9736_4 98.71 0.55 15

Istrumet Calibratio The SMU`s PSM prepared gravimetrically i accordig to ISO 614 was used for the oe poit calibratio of the aalyzer before each measuremet (100 µmol/mol). MY9741_4 xso = 99.68 µmol/mol. Pressure: 73.5 mmhg Flow: 0.487 l per mi. Itegratio time: 30 sec Sample Hadlig Before each measuremet all of PSM used as well as ukow mixture was stabilized for h to laboratory temperature ad homogeized. Before the collectig the data, all coectios ad juctios were checked to avoid a leakages. The pressure ad flow of all PSM ad sample was stabilized for 5 miutes to esure the same eviromets. Ucertaity table: Ucertaity source Xi Estimate xi (μmol/mol) Assumed distributio Stadard ucertaity u(xi) (μmol/mol) Sesitivity coefficiet ci Cotributio to stadard ucertaity ui(y) (μmol/mol) Resolutio 0.1 rectagular 0.03 1 0.03 Maximal drift 0.6 rectagular 0.17 1 0.17 Calibratio stadard 99.68 ormal 0.56 1 0.56 Arithmetic mea 100.31 ormal 0.3 1 0.3 x SO 0.63 Coverage factor: Expaded ucertaity: 1.6 μmol/mol 16

Ukrmetrteststadart report Key compariso of primary stadards of compoets cotet i gaseous media CООМЕТ 484/RU/09: SО i itroge (100 mol/mol)» MEASUREMENT REPORT I. Results of experimetal study Laboratory: Ukrmetrteststadart, Kiev, Ukraie cylider No: S198746 Measuremet 1 Result ( mol/mol) x _ Relative stadard deviatio S( x _ ) Number of submeasuremets Sulfur dioxide 07.06.01 100,48 0,18 10 Measuremet Result ( mol/mol) x _ Relative stadard deviatio S( x _ ) Number of submeasuremets Sulfur dioxide 11.06.01 99,76 0,07 10 Measuremet 3 Result ( mol/mol) x _ Relative stadard deviatio S( x _ ) Number of submeasuremets Sulfur dioxide 14.06.01 100,17 0,48 10 Fial results: Gas mixture Result ( mol/mol) Coverage factor Expaded ucertaity ( mol/mol) Sulfur dioxide 100,14 1,03 17

II. Descriptio of the study Istrumet(s) Compoet mass measuremets durig the preparatio of primary stadard gas mixtures (PSGM) of SO i itroge were carried out with XP6003L electroic scales, produced by Mettler Toledo (Max 6,1 kg, Mi 0, g, stadard deviatio 0,003 g) usig substitutio method of measuremet with weights traceable to PTB, Germay. Data were collected automatically. Paret gas purity aalysis was carried out usig НР6890N chromatographs with HID, PID, TCD ad MSD detectors, as well аs GIAM-15M ad Oix gas aalyzers. Gas purity data were collected automatically. Measuremets of SO cotet i itroge were made usig PSGM ad model 100E gas aalyzer produced by Teledye Advaced Pollutio Istrumetatio (USA). The priciple of operatio of 00EH gas aalyzer is chemilumiescece. Data were collected automatically. Calibratio stadards primary stadard gas mixtures (PSGM) PSGM used for compariso were prepared i alumium cyliders with «Aqulife 4 + Aqulife 3 log cycle» specialized coatigs usig gravimetric method as specified i DSTU ISO 614-003. Gas compoet mass measuremets were made with XP6003L electroic scales produced by Mettler Toledo (Max 6,1 kg, Mi 0, g, stadard deviatio 0,003 g) usig weight substitutio method with weights traceable to PTB, Germay. Data were collected automatically. PSGM were prepared i stages usig dilutio techique. Paret gas purity aalysis tests were carried out usig НР6890N chromatographs with HID, PID, TCD ad MSD detectors, as well аs GIAM-15M ad Oix gas aalyzers. Data were collected automatically. Prepared PSGM were checked usig previously maufactured PSGMs i accordace with DSTU ISO 6143-003. Ucertaity estimatio of compoet cotet was carried out i accordace with DSTU ISO 614-003 usig GravCalc Ver..3.1 software produced by NPL, UK. 18

Compositio of calibratio referece materials: Table 1 - Primary stadard gas mixtures (PSGM) used for measuremets of SO i itroge: Состав PSGM-1 Cylider 90080 x, ( mol/mol) u(x), % rel. PSGM- Cylider 90089 x, ( mol/mol) u(x), % rel. PSGM-3 Cylider D8394737 x, u(x), % rel. ( mol/mol) SO 95,03 0,037 100,16 0,036 105,0 0,038 N balace balace balace Note: x mole fractio, u(x) relative stadard ucertaity. Calibratio ad measuremets To calibrate the 100E gas aalyzer, PSGMs close by cotet to the aalyzed gas mixture were used. Accordig to the results of the regressio aalysis of calibratio data ad the data o the compositio of PGSMs, the aalytical fuctio for determiig the cotet of the measured compoet i the sample was liear: x(y)=b 1 y+b 0 After calibratio the 100 Е gas aalyzer was used as a comparator. Five idepedet comparisos were carried out i repeatability coditios. Durig the compariso the gas mixtures were let ito comparator i followig order: PSGM-1 х 10; PSGM - х 10; Gas mixture CООМЕТ-1 х 10; PSGM - х 10; PSGM -3 х 10. Therefore, oe measuremet icluded 10 observatios. Sample Hadlig Hadig of the PSGMs ad samples was carried out accordig to DSTU ISO 16664:005. The cyliders were kept for 4 hrs i the laboratory where comparators were located. The room was thermostatically cotrolled at t = (0 ± ) С. Samples were supplied to the comparator with flow stabilizatio. 19

Ucertaity calculatio Ucertaity table Ucertaity source X j Type of evaluati o x j Estimated distributio Stadard ucertaity u(x j ), % rel. Sesitivity factor c j Cotributio to stadard ucertaity u j (y), % rel. Calibratio PSGM B ormal 0,04 1 0,04 Compariso A, B ormal 0,5 1 0,5 Coverage factor: Expaded ucertaity:1,0 % rel. 0

VNIIM report COOMET.QM-K76 (COOMET project 484/RU/09) Key compariso of primary stadard gas mixtures: SO i Nitroge (100 μmol/mol) MEASUREMENT REPORT I. Results of study Laboratory: D.I.Medeleyev Istitute for Metrology (VNIIM) Cylider umber: D48475 Measuremet 1 Result ( mol/mol) Stadard deviatio (% relative) Number of sub measuremets Sulfur dioxide 19.01.01 99,98 0,0 4 Measuremet Result ( mol/mol) Stadard deviatio (% relative) Number of sub measuremets Sulfur dioxide 31.08.01 100,18 0,07 4 Measuremet 3 Result ( mol/mol) Stadard deviatio (% relative) Number of sub measuremets Sulfur dioxide 4.09.01 100,13 0,08 Fial results: Gas mixture Result (assiged value) mol/mol Coverage factor Assiged expaded ucertaity mol/mol Sulfur dioxide 100,10 0,0 1

II. Descriptio of study Istrumet(s) Priciples, make, type, cofiguratio, data collectio etc. Measuremet method: UV absorptio Istrumet: Spectrophotometer Lambda 900 ( Perki Elmer, USA), Legth of the cell 14 cm, Wave legth 06,7 m, Resolutio 5 m, Data were collected automatically. Calibratio Stadards Calibratio Stadards for the measuremets (preparatio method, purity aalyses. estimated ucertaity etc.) Calibratio gas mixtures for the compariso were prepared gravimetrically i accordace with requiremets of ISO 614. Preparatio оf gas mixtures was carried out of pure substaces by 3 stage dilutio: 1-st stage* level 1,5 %; -d stage level 0,1 %; 3-rd stage target mixtures 100 mol/mol. There were prepared 3 calibratio gas mixtures of the target cocetratio. Alumium cyliders (Luxfer, 5 L) with Aculife treatmet (1 cylider) ad without special treatmet ( cyliders) were used for this purpose. Note Gas mixtures of 1-st stage* (level 1,5 %) were prepared i May 010 withi CCQM- K76 compariso, where VNIIM showed cosistet results (D i,rel =0,37 %, U(D i ) rel =0,7 %). All the other mixtures were prepared withi the preset compariso. Purity tables for the paret pure gases are show i the Tables 1 ad. Table 1 Pure SO Compoet Mole fractio, mol/mol H SO 4 100 50 H O 100 50 As 0,0150 0,0075 SO 999800 70 Stadard ucertaity, mol/mol

Table : Pure N Compoet Mole fractio, mol/mol H O 4,0 0, O 1,06 0,0 Ar 0,40 0,04 CO 0,069 0,005 CO 0,061 0,005 CH 4 0,015 0,009 H 0,0005 0,0003 N 999994,39 0,3 Stadard ucertaity, mol/mol Istrumet Calibratio Calibratio procedure (mathematical model/calibratio curve, umber ad cocetratios of stadards, measuremet sequece, temperature/pressure correctio etc.) Sigle poit calibratio method was used to determie SO mole fractio i the gas mixture to be ivestigated. Metrological characteristics of the 3 prepared calibratio gas mixtures are show i the Table 3 Table 3: Calibratio gas mixtures Gas mixture Mole fractio, mol/mol Stadard ucertaity, mol/mol 1 SO /N 100,15 0,047 SO /N 100,37 0,047 3 SO /N 100,48 0,047 Measuremet sequece was i the order: stadard1 - sample - stadard1- stadard sample - stadard (etc.). Temperature ad pressure correctios were ot applied due to use of above-metioed measuremet sequece. Sample Hadlig How were the cyliders treated after arrival (e.g. stabilized) ad how were samples trasferred to the istrumet? (automatic, high pressure, mass-flow cotroller, dilutio etc) Prior to measuremets the cyliders were stabilized to room temperature at least for 4 hours. Each cylider was equipped with a stailess steel fie meterig valve that had bee thoroughly purged by the aalyzed gas mixture before measuremets. The sample was fed ito the cell through fluoroplastic tube at a flow rate 0,5 dm 3 /mi. The cell was purged 10 mi by the aalyzed gas mixture before measuremets. After each measuremet pure Nitroge was flushed through the spectrophotometer. 3

Ucertaity table: Ucertaity source Estimate Xi xi, mol/mol Calibratio stadards (weighig + purity) Assumed distributio Stadard ucertaity u(xi) mol/mol Sesitivity coefficiet ci Cotributio to stadard ucertaity ui(y), mol/mol 100,37 Normal 0,047 0,997 0,047 Istrumet respose 100,10 Normal 0,08 1 0,08 Combied stadard ucertaity: 0,10 mol/mol Coverage factor: k= Expaded ucertaity:0,0 mol/mol 4