international key comparison coomet.qm-k1а – carbon … · 2010-02-16 · international key...

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International Key Comparison COOMET.QM-K1а – Carbon monoxide in nitrogen Final report L.A. Konopelko1, Y.A. Kustikov1, E.V. Gromova1, M.S. Rozhnov2, V.N. Ananyin3, A.S. Kluchits, H.-J. Heine4 1D.I.Mendeleyev Institute for Metrology (VNIIM), Research Department for the State Standard in the Field of Physical-Chemical Measurements (PCD), 19, Moskovsky pr., St-Petersburg, 190005, Russia 2All Ukrainian State Research-Industrial Center of Standardization, Metrology, Certification and Protection of Consumers (Ukrmetrteststandard), 4, Metrologicheskaya str., Kiev, 03143, Ukraine. 3Belorussian State Institute for Metrology (BelGIM), Department of Physical, Chemical and Optical measurements, sector of verification gas mixtures and standards, 93, Starovilensky trakt, Minsk, 220053, Belarus. 4Federal Institute for Materials Research and Testing (BAM), AG I.41 Gasanalysis, Unter den Eichen 87, D-12205 Berlin, Germany. Field Amount of substance: gas analysis Subject Key comparison: Standard reference materials – gas mixtures CO in nitrogen. Participants: Institute City Country VNIIM Saint-Petersburg Russia Ukrmetrteststandard Kiev Ukraine BelGIM Minsk Belarus BAM Berlin Germany Organizing body TC 1.8 «Physical Chemistry» COOMET Rationale This comparison is the second key comparison in the field of gas analysis organized by Technical Committee 1.8 “Physical Chemistry” COOMET. The comparison was registered in the international database on key comparison (KCDB), Appendix B of MRA, as COOMET.QM-K1а. Earlier the key comparison was carried out by Consultative Committee for Amount of Substance CCQM-К1а (CO in Nitrogen) (the results were published in 1999) [1]. Foundation of this comparison: • Recognition of national measurement standards of Belarus and Ukraine and entering of calibration and measurement capabilities (CMC) of BelGIM and Ukrmetrteststandard to the (KCDB) of the BIPM in accordance with the Mutual Recognition Arrangement (CIPM MRA) for national measurement standards and for calibration and measurement certificates issued by NMIs; • Objective of NMIs which participated in the comparison CCQM-K1a (BAM, VNIIM) is to support or improve their CMCs.

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Measurement standards Gas mixtures for the comparison were prepared by means of gravimetry and were studied thoroughly regarding its composition and stability at the coordinating laboratory (VNIIM PCD). The concentrations of CO in gas mixtures lie within the following range: Component Nominal value, 10-4 mol/mol

1. СО N2

0,9 – 1,1 Balance

2. СО N2

9 – 11 Balance

Schedule The cylinders with gas mixtures were sent out to all the participants of the comparison in November 2007. The measurement results were submitted by the participants in March – April 2008. As a result of difficulties in the customs the cylinders were shipped back to the coordinating laboratory in May 2008. The date of re-analysis of the gas mixtures was prolonged till June 2008. Measurement protocol The measurement model has been taken from the key comparison CCQM-K1a. The measurement protocol requested each laboratory to perform at least 3 measurements obtained under repeatability conditions including at least 3 separate calibrations. The protocol of the comparison informed the participants about the nominal concentration ranges. The laboratories were requested to submit the measurement report with the calculation of the uncertainty budget. Measurement equation The gas mixtures for the comparison were prepared by means of gravimetry in accordance with the requirements of ISO 6142 [2] and were studied thoroughly regarding its composition and stability at the coordinating laboratory (VNIIM PCD) in accordance with the requirements of ISO 6143 [3]. Twelve gas mixtures were prepared, six of which were sent to the participants for studying (two mixtures for each laboratory). Three groups of uncertainty sources were considered during the gravimetric preparation of the gas mixtures: 1. gravimetric preparation (weighing process) 2. purity of the parent gases 3. stability of the gas mixtures There were no evidence of the effect of adsorption, this gas component has been known as a very stable compound. Therefore, only the first two groups of uncertainty components appear in the model for evaluating the uncertainty from gravimetric preparation.

)()()( 222purityweighinggravp xuxuxu ∆+= (1)

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The second contributor to the uncertainty of the reference value of gas mixtures ugravR is the uncertainty from verification u(xver). The verification process is used to confirm the gravimetric composition according to ISO 6143 [3]. NDIR analyzer which is a part of the National Primary Measurement Standard GET 154-01 was used for the verification.

gravRgravR kuU = (2) where

)()( 22vergravpgravR xuxuu += (3)

k=2 In order to determine the link between COOMET.QM-K1a and CCQM-K1a it is necessary to calculate gravRU * taking into account deviation of VNIIM in CCQM-K1a:

aKCCQMgravRgravR xUU 122* )( −∆+= (4)

where aKCCQM 1−∆ - deviation of VNIIM in CCQM-K1a from gravimetric value. The values of aKCCQM 1−∆ for VNIIM the following:

VNIIM CCQM-K1a

aKCCQM 1−∆ , %

CO 100·10-6 mol/mol - 0,36 CO 1000·10-6 mol/mol 0,12

Measurement methods and calibration procedures The following methods of measurement and calibration methods have been employed (table 1). Table 1 Measurement and calibration methods

Laboratory Measurement method Calibration method Total number of measurements

VNIIM NDIR bracketing

3 measurements 5 sub-measurements

Ukrmetrteststandard NDIR (100·10-6 mol/mol) NDIR (1000·10-6 mol/mol)

three points, linear three points, linear

3 measurements 10 sub-measurements 4 measurements 5 sub-measurements

BelGIM NDIR (100·10-6 mol/mol) ГХ с детектором ДТП (1000·10-6 mol/mol)

three points, linear three points, linear

3 measurements 5 sub-measurements 4 measurements 5 sub-measurements

BAM GC-FID with methanizer (100·10-6 mol/mol) GC-FID with methanizer (1000·10-6 mol/mol)

bracketing bracketing

4 measurements 6*3 sub-measurements 3 measurements 6*3 sub-measurements

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Results In the current comparison on gas mixtures, measurements were performed on individually prepared gas mixtures with (slightly) different concentrations. The individual gravimetric values are reference values. The difference between the analyzed and gravimetric values has been taken as the degree of equivalence Di, defined as

igravilabi xxD ,, −= (5) The combined standard uncertainty of the degree of equivalence can be expressed as

2*,

2, )()( igravRilabi uuDu += (6)

The expanded uncertainty )( iDU of the degree of equivalence Di is

2*,

2, )()( igravRilabi uukDU += (7)

Where Di Degree of equivalence, difference between the laboratory value and the gravimetric value U(Di) Expanded uncertainty of the degree of equivalence

gravx Assigned amount of substance fraction of a component

labx Result as reported by the participant gravRu* Standard uncertainty of gravx in view of deviation of VNIIM in the CCQM-K1a

labu Standard uncertainty of labx k Coverage factor, 2=k All the results of this key comparison are presented in the tables 2 and 3 and shown in figures 1 and 2. The tables 2 and 3 contain the following information: Lab Laboratory Cylinder Identification code of cylinder

gravx Assigned amount of substance fraction of a component

gravRU Expanded uncertainty of gravx , 2=k

gravRU * Expanded uncertainty of gravx , 2=k in view of deviation of VNIIM in the CCQM-K1a

labx Result as reported by the participant

labU Expanded uncertainty of labx Di Degree of equivalence

)( iDU Expanded uncertainty of Di

labk Coverage factor as reported by a participant Calculation of expanded uncertainty was carried out with coverage factor k =2.

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Degrees of equivalence The unilateral degree of equivalence has already been defined (5). The degree of equivalence between two laboratories is defined as:

{ } { }jgravjlabigravilabij xxxxD ,,,, −−−= (8) where

igravx , - the assigned value for the laboratory i;

ilabx , - the amount of substance fraction of the laboratory i;

jgravx , - the assigned value for the laboratory j;

jlabx , - the amount of substance fraction of the laboratory j. The expanded uncertainty of the degree of equivalence Dij (k=2):

2,

2,

2*,

2, )()( jgravRjlabigravRilabij uuuukDU +++= (9)

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Table 2: Results for СО 100·10-6 mol/mol Laborato

ry Cylinder

gravx (10-6

mol/mol)

gravRU (10-6

mol/mol)

gravRU * (10-6

mol/mol)

labx (10-6

mol/mol)

labU (10-6

mol/mol)

labk

D, (10-6

mol/mol)

gravxD / %

k )(DU , (10-6

mol/mol)

gravxDU /)( , %

VNIIM D95 5087 100,340 0,1 0,37 100,306 0,18 2 -0,034 -0,034 2 0,41 0,41 Ukrmetrteststandard

D95 5090 100,055 0,1 0,37 99,5 0,6 2 -0,555 -0,555 2 0,71 0,71

BelGIM D95 5061 100,282 0,1 0,37 100,6 1,5 2 0,318 0,317 2 1,55 1,54 BAM D20 0286 100,352 0,1 0,37 100,253 0,4 2 -0,099 -0,099 2 0,55 0,55 Table 3: Results for СО 1000·10-6 mol/mol Laborato

ry Cylinder

gravx (10-6

mol/mol)

gravRU (10-6

mol/mol)

gravRU * (10-6

mol/mol)

labx (10-6

mol/mol)

labU (10-6

mol/mol)

labk

D, (10-6

mol/mol)

gravxD / %

k )(DU , (10-6

mol/mol)

gravxDU /)( , %

VNIIM D20 0365 1004,17 1,0 1,59 1004,76 1,6 2 0,59 0,059 2 2,26 0,22 Ukrmetrteststandard

D20 0354 1011,84 1,0 1,59 1012,0 5,0 2 0,16 0,016 2 5,25 0,52

BelGIM D20 0381 1006,45 1,0 1,59 1009,4 9,3 2 2,95 0,293 2 9,44 0,94 BAM D20 0285 1004,05 1,0 1,59 1004,75 3,0 2 0,70 0,070 2 3,40 0,34

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COOMET.QM-K1a СО in Nitrogen 100*10-6 mol/mol

-3

-2

-1

0

1

2

3D/

Xgra

v, %

rel

VNIIMUkrmetrtest-

standard BelGIM BAM

Figure 1 Degree of equivalence СО 100·10-6 mol/mol

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COOMET.QM-K1a СО in Nitrogen 1000*10-6 mol/mol

-3

-2

-1

0

1

2

3D/

Xgra

v, %

rel

VNIIMUkrmetrtest-

standard BelGIM BAM

Figure 2 Degree of equivalence СО 1000·10-6 mol/mol

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Discussion and conclusions All the laboratories find the gravimetric value within ± 0,6 % relative to the gravimetric value of coordinating laboratory (for CO 100·106 mol/mol) and within ± 0,3 % relative to the gravimetric value (for CO 1000·106 mol/mol). This is a satisfying result. For all the laboratories the observed difference between the gravimetric and reported values does not exceed its combined uncertainty. VNIIM and BAM are link laboratories for CCQM-K1. Reference [1] A.Alink, M.J.T.Milton, F.Guenther, E.W.B. de Leer, H.J.Heine, A.Marschal, Gwi Suk Heo, C.Takahashi, Wang Lin Zhen, Y.Kustikov, E.Deak, Final Report of Key Comparison CCQM-K1. [2] International Organization for Standardization, ISO 6142:2001 Gas analysis - Preparation of calibration gas mixtures - Gravimetric methods, 2nd edition. [3] International Organization for Standardization, ISO 6143:2001 Gas analysis – Comparison methods for determining and checking the composition of calibration gas mixtures. Coordinator Leonid Konopelko 1D.I.Mendeleyev Institute for Metrology (VNIIM), Research Department for the State Standard in the Field of Physical-Chemical Measurements (PCD), 19, Moskovsky pr., St-Petersburg, 190005, Russia Tel: +7 812 315 11 45 Fax: +7 812 327 97 76 E-mail: [email protected] Completion Date November 2008

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Annex 1: Proposal of Degrees of Equivalence Table 1. Degrees of Equivalence СО 100·10-6 mol/mol

Lab i Di U(Di) 10-6 mol/mol VNIIM -0,034 0,41 Ukrmetrteststandard -0,555 0,70 BelGIM 0,318 1,54 BAM -0,099 0,54

Table 2. Degrees of Equivalence СО 1000·10-6 mol/mol

Lab i Di U(Di) 10-2 mol/mol VNIIM 0,59 2,26 Ukrmetrteststandard 0,16 5,25 BelGIM 2,95 9,43 BAM 0,70 3,40

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Annex 2: Measuring reports as submitted by participating laboratories

D.I.MENDELEYEV INSTITUTE FOR METROLOGY (VNIIM) RESEARCH DEPARTMENT FOR THE STATE MEASUREMENT STANDARDS IN

THE FIELD OF PHYSICO-CHEMICAL MEASUREMENTS

Key Comparison COOMET.QM-K1a CO in Nitrogen (100·10-6 mol\mol and 1000·10-6 mol\mol)

REPORT

Date: 24.11.08

Authors: L.A. Konopelko

Y.A. Kustikov V.V. Pankratov A.V. Kolobova

E.V. Gromova

Reference method: NDIR Instrument: Multichannel automatic NDIR analyzer included to the set of the National

Primary measurement standard of units of mole fraction and mass concentration of components in gas medium, GET 154-01.

Calibration standards Characteristics of pure substances used for preparation of the calibration standards are

shown in tables 1-2.

Table 1 – Purity table for CO

Component Mole fraction 10-6 mol/mol

Expanded uncertainty 10-6 mol/mol

(k=2) H2 13,20 0,3 O2+Ar 14,94 0,42 N2 992,9 9,5 CO2 26,86 0,28 CH4 0,5 0,26 H2O 265,0 26,5 CO 998686,60 28,16

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Table 2 – Purity table for N2

Component Mole fraction 10-6 mol/mol

Expanded uncertainty 10-6 mol/mol

(k=2) H2 0,005 0,003 Ar 11,9 0,5 O2 3,6 0,2 CH4 0,005 0,003 СО 0,008 0,0046 СО2 0,096 0,005 H2O 3,2 0,1 N2 999981,19 0,55 All standard gas mixtures were prepared in aluminium cylinders,

V= 10 L. Weighing was performed on the balances 81-V-HCE-20kg (hnu-Voland, USA).

Experimental standard deviation: 8 mg. Preparation of standard gas mixtures CO/N2 1000·10-6 mol\mol was carried out in 2 stages: - preparation of the first gas pre-mixtures CO/N2 6·10-2 mol\mol. - preparation of the calibration gas mixtures CO/N2 1000·10-6 mol\mol. Preparation of standard gas mixtures CO/N2 100·10-6 mol\mol was carried out in 3 stages

where gas mixtures CO/N2 6·10-2 mol\mol and 1000·10-6 mol\mol were used as pre-mixtures. The characteristics of calibration standards are shown in tables 3 and 4. Table 3 – Characteristics of calibration standards CO/N2 100·10-6 mol\mol Standard gas mixture N

Component Assigned value, 10-6 mol/mol

Relative standard uncertainty, %

CO 99.760 0.1 1 N2 balance - CO 98.342 0.1 2 N2 balance - CO 102.013 0.1 3 N2 balance -

Table 4 – Characteristics of calibration standards CO/N2 1000·10-6 mol\mol Standard gas mixture N

Component Assigned value, 10-6 mol/mol

Relative standard uncertainty, %

CO 1016.91 0.09 1 N2 balance - CO 1002.35 0.1 2 N2 balance - CO 987.77 0.09 3 N2 balance -

Instrument calibration For the instrument calibration the bracketing technique was used.

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Sample handling Prior to measurements the cylinders were stabilized to room temperature. Results of measurements Results of measurements of CO mole fraction in the gas mixtures CO/N2 100·10-6 mol\mol

and 1000·10-6 mol\mol are shown in the tables 5 and 6. Table 5 - Results of measurements of CO mole fraction in cylinder № D955087 (100·10-6 mol\mol) Measurement #1 Component Date

(dd/mm/yy) Result (10-6 mol/mol)

Standard deviation (% relative)

number of submeasurements

CO 19/10/07 100.331 0.03 5

Measurement #2 Component Date




СО 25/10/07 100.346 0.03 5





CO 31/10/07 100.241 0.05 5 Table 6 - Results of measurements of CO mole fraction in cylinder № D200365 (1000·10-6 mol\mol) Measurement #1 Component Date




CO 04/10/07 1004.17 0.02 5





СО 12/10/07 1005.01 0.03 5





CO 06/11/07 1005.11 0.05 5

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Evaluation of uncertainty of measurements Total standard uncertainty of CO mole fraction was calculated on the base of the following

constituents: - standard uncertainty of CO mole fraction in calibration gas mixture (including

uncertainty of weighing of parent gases and pre-mixtures, uncertainty in the purity of the parent gases, uncertainty from verification);

- standard uncertainty of calibration; - standard deviation of the measurement result of CO mole fraction in the investigated gas

mixtures. Uncertainty budgets for CO mole fraction in gas mixtures 100·10-6 mol\mol and 1000·10-

6 mol\mol are shown in the tables 7 and 8. Table 7– Uncertainty budget for CO mole fraction in cylinder № D955087 (100·10-6 mol\mol)

№ Source of uncertainty Type of evaluation

Standard uncertainty, % relative

1 Preparation of the calibration gas mixtures А, B 0,05

2 Standard uncertainty of calibration A 0,04 3 Standard deviation of the measurement result A 0,06

Combined standard uncertainty 0,09 Expanded uncertainty (k=2) 0,18

Table 8– Uncertainty budget for CO mole fraction in cylinder № D200365 (1000·10-6

mol\mol)

№ Source of uncertainty Type of evaluation

Standard uncertainty, % relative

1 Preparation of the calibration gas mixtures А, B 0,05

2 Standard uncertainty of calibration A 0,03 3 Standard deviation of the measurement result A 0,06

Combined standard uncertainty 0,08 Expanded uncertainty (k=2) 0,16

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Final results of measurements Final results of measurements of CO mole fraction in investigated gas mixtures are shown

in the table 9 and 10. Table 9 – Results for CO mole fraction in cylinder № D955087 (100·10-6 mol\mol)

Component Result (10-6 mol/mol)

Expanded Uncertainty

(10-6 mol/mol)

Relative Expanded

Uncertainty (%) Coverage factor

CO 100.306 0.18 0.18 2

Table 10 – Results for CO mole fraction in cylinder № D200365 (1000·10-6 mol\mol)

Component Result (10-6 mol/mol)

Expanded Uncertainty

(10-6 mol/mol)

Relative Expanded

Uncertainty (%) Coverage factor

CO 1004.76 1.6 0,16 2

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KEY COMPARISON COOMET N 401/RU/07 COMPARISON OF GAS MIXTURE COMPOSITION STANDARDS

CO in N2 nitrogenе (0,1 mmol/mol and 1 mmol/mol)»

MEASUREMENT REPORT

I. Results of experimental study

Laboratory: Ukrmetrteststandart, Kiev, Ukraine

NOMINAL COMPOSITION VALUES:

Cylinder number: 5090 CO - 0,9·10-4 – 1,1·10-4 mol/mol Nitrogen - balance

Cylinder number: 0354 CO - 9·10-4 – 11·10-4 mol/mol Nitrogen - balance

1. CO/nitrogen (0,1 mmol/mol) cylinder No 5090

Measurement No 1

Date

Result (mol/mol)

x_

Relative standard deviation

S( x_

), %

Number of sub-

measurementsn

Carbon monoxide 31.01.2008 0,9936·10-4 0,35 10

Measurement No 2

Date

Result (mol/mol)

x_


S( x_

), %

Number of sub-

measurements

Carbon monoxide 06.02.2008 0,9946·10-4 0,35 10

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Measurement No 3

Date

Result (mol/mol)

x_


S( x_

), %

Number of sub-

measurements

Carbon monoxide 14.02.2008 0,9941·10-4 0,31 10

2. CO/nitrogen (1 mmol/mol) cylinder No 0354

Measurement No 1

Date

Result (mol/mol)

x_


S( x_

), %

Number of sub-

measurements

Carbon monoxide 06.02.2008 10,115·10-4 0,29 10

Measurement No 2

Date

Result (mol/mol)

x_


S( x_

), %

Number of sub-

measurements

Carbon monoxide 05.03.08 10,117·10-4 0,19 5

Measurement No 3

Date дд/мм/гг

Result (mol/mol)

x_


S( x_

), %

Number of sub-

measurements

Carbon monoxide 06.03.08 10,119·10-4 0,31 5

Measurement No 4

Date

Result (mol/mol)

x_


S( x_

), %

Number of sub-

measurements

Carbon monoxide 07.03.08 10,113·10-4 0,52 5

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Final results:

1. CO/nitrogen (0,1 mmol/mol) cylinder No 5090

Gas mixture Result (mol/mol) Coverage factor Expanded uncertainty (mol/mol)

Carbon monoxide 0,995⋅10-4 2 0,006⋅10-4

2. CO/nitrogen (1 mmol/mol) cylinder No 0354

Gas mixture Result (mol/mol) Coverage factor Expanded uncertainty (mol/mol)

Carbon monoxide 10,12⋅10-4 2 0,05⋅10-4

II. Description of the study

Instrument(s) Gas analyzer 300E produced by Teledyne Advanced Pollution

Instrumentation (USA) and gas chromatographs НР 6890 belonging to the Ukrainian national primary standard of mole fraction unit of gaseous components (DETU 05-01-2003).

Градуировочные стандартные образцы All the primary standard gas mixtures (PSGM) used for calibration were

prepared gravimetrically from pure gases according to ISO 6142 using Mettler Toledo electronic balance КА-20-3, maximum capacity 20 kg, minimum weighing limit 0,1 g, standard deviation is 0,006 g.

Purity analysis of parent gases was carried out using НР6890N chromatographs with HID, FID, TCD and MSD detectors, as well аs GIAM-15M and Onix gas analyzers. Prepared PSGMs have been verified by analytical comparisons with existing gravimetrically prepared PSGMs according to ISO 6143.

Composition of calibration standards: Calibration standards – primary standard gas mixtures (PSGM) used for

measurements by comparison method:

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for CO/nitrogen (0,1 mmol/mol)

PSGM-1 Cylinder No 8306

PSGM-2 Cylinder No 7122A

PSGM-3 Cylinder No 8327 Composition

x, % u(x) , % x, % u(x) , % x, % u(x) , % CO 0,0099 0,2 0,0104 0,2 0,0109 0,2 N2 balance – balance – balance –

for CO/nitrogen (1 mmol/mol)

PSGM-4

Cylinder No D340100 PSGM-5

Cylinder No D340094 PSGM-6

Cylinder No D340079 Composition x, % u(x) , % x, % u(x) , % x, % u(x) , %

CO 0,0978 0,1 0,1013 0,2 0,1030 0,2 N2 balance – balance – balance –

Note: x – mole fraction, u(x) – relative standard uncertainty, %

Calibration and measurements Three independent measurements were carried out for CO/nitrogen (0,1 mmol/mol) and four independent measurements were carried out for CO/nitrogen (1 mmol/mol) under repeatability conditions.

Each measurement included ten sub-measurements for CO/nitrogen (0,1 mmol/mol) and five sub-measurements for CO/nitrogen (1 mmol/mol).

Calibration and measurement methods

Laboratory Measurement method Type of calibration curveUkrmetrteststandart NDIR 3 points, linear

Sample Handling

Handing with PSGM and samples – according to ISO 16664:2003. The cylinders were kept for 24 hrs in the room where comparators were located. The room was thermostatted at t = (20 ± 2) ºС.

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Uncertainty calculation Uncertainty table for CO/nitrogen (0,1 mmol/mol)

Uncertainty source Xj Type of evaluation

Relative standard uncertainty

u(xj), %

Sensitivity factor

cj

Contribution to relative standard

uncertainty uj(y), %

Calibration PSGM B 0,2 1 0,2 Comparison A, B 0,2 1 0,2 Coverage factor: 2 Expanded uncertainty: 0,6 % Uncertainty table for CO/nitrogen (1 mmol/mol)

Uncertainty source Xj Type of evaluation

Relative standard uncertainty

u(xj), %

Sensitivity factor

cj

Contribution to relative standard

uncertainty uj(y), %

Calibration PSGM B 0,15 1 0,15 Comparison A, B 0,2 1 0,2 Coverage factor: 2 Expanded uncertainty: 0,5 %

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Key comparisons КООМЕТ.QM – K1.a «Comparison standards - gas СО-mixtures in nitrogen»

REPORT ON RESEARCH RESULTS

I. Results of experimental research

Laboratory: Belarus, BelGIM, Department of physical, chemical and optical measurements, sector of verification has mixtures and standards, 8, Serova str., Minsk, . Vessel number: D 95 5061. Content of СО - 0,9*10-4 – 1,1*10-4 mol/mol.

1. СО/ nitrogen (0,1 mmol/mol)

Measurement №1

Date

Result (10-4 mol/mol)

x_

Standard deviation

S( x_

), % rel.

Number of observations

n

Carbon oxide 09.01.2008 1,0044 0,159 5

Measurement №2

Date


x_

Standard deviation

S( x_

), % rel.


n

Carbon oxide 11.01.2008 1,0101 0,296 5

Measurement №3

Date


x_

Standard deviation

S( x_

), % rel.


n

Carbon oxide 14.01.2008 1,0048 0,179 5

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Vessel number: D 20 0381. Content of СО - 9*10-4 – 11*10-4 mol/mol. 2. СО/ nitrogen (1 mmol/mol)

Measurement №1

Date


x_

Standard deviation

S( x_

), % rel.


n

Carbon oxide 10.01.2008 10,101 0,214 5

Measurement №2

Date


x_

Standard deviation

S( x_

), % rel.


n

Carbon oxide 14.01.2008 10,109 0,247 5

Measurement №3

Date


x_

Standard deviation

S( x_

), % rel.


n

Carbon oxide 16.01.2008 10,097 0,223 5

Measurement №4

Date


x_

Standard deviation

S( x_

), % rel.


n

Carbon oxide 18.01.2008 10,069 0,280 5

Final results

1. СО/ nitrogen (0,1 mmol/mol). Vessel number: D 95 5061

Gas mixture Result

(10-4 mol/mol) Coverage factor Extended uncertainty

(10-4 mol/mol) Carbon oxide 1,006 2 0,015

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2. СО/ nitrogen (1 mmol/mol). Vessel number: D 20 0381

Gas mixture Result

(10-4 mol/mol) Coverage factor Extended uncertainty

(10-4 mol/mol)

Carbon oxide 10,094 2 0,093

II. Description of research

Equipment (principle of operation, type, configuration, data acqusition method etc.)

During analysis of standard gas mixture (SGM) 0,1 mmol/mol of СО in nitrogen, as comparator it was used two-channel optic acoustic gas analyzer GIAM-15m. Scale: 0 – 200 ppm. Analasys of SGM 1 mmol/mol СО in nitrogen was performed on gas chromatograph. HP – 6890N with DTP. Carrier gas – helium 99,9999. Separation capillary column «HP – Molesieve» with the length of 30 m. Graduation reference materials – calibration gas mixtures (CGM) 1. Quantity compound of CGM is determined by the gravimetric method in

accordance with ISO 6142: 2001. Components content in CGM is expressed in molar fractions. Uncertainty of the

CGM compound is represented as extended uncertainty with coverage factor of 2. Molar masses of the components and their uncertainty are taken from ISO 14912:

2003. Technical and metrological characteristics of the equipment used in gravimetric

CGM preparation are provided in the Table 1. Table 1 Name of the

equipment Manufacturer Metrological characteristics

Weights, mass comparator

Type КА10-3/Р

Mettler-Toledo, Switzerland

Measurement limit: 15 kg; Count range (scale division): 1 mg; AQD - 1,8 mg at the load of 10 kg; Working temperature range: +10÷30°С; temperature change during 1 h. not more than ±0,5 °С.

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Unit for gases mixing by the method of static pressure

OKB «Academicheskoye

», Belarus

Measurement limits: 0,00025 ÷ 10,0 MPa Manometers accuracy class – 0,15; Vacuumeter accuracy class – 0.25;

2. Analysis of source gases purity

Data on source gases purity are taken from the supplier passports and from the results of analysis of the impurities content in the pure gases on MMP developed in BelGIM. Compound of source gases, used for preparation of mixtures for calibration is provided in the Table 1.

Table 2 – Metrological characteristics of source gases.

«Pure» gas Component Content,

molar fraction, %

Standard uncertainty, molar

fraction, % CO 99,860 0,0010 N2 0,132 0,0005 O2 0,002 0,0005

Carbon oxide ТU 6-02-7-101-85 Vessel № 292551 Manufacturer: Russian Federation СO2 0,003 0,0001

N2 99,902 0,0010 СО 0,00006 0,00003

Ar+O2 0,0795 0,0001

Nitrogen GOST 9293-74 Vessel № 913 Manufacturer: Russian Federation H2O 0,00023 0,00003

After completion of the mixture preparation the vessel was stored in the

laboratory premisis within 24 h, and then the mixture was additinallly homogenized at the stand by rotation on roll mills during 4-5 hours.

3. Graduation and calibration of the equipment During equipment calibration calibration gas mixtures were used that are

identical (by compuond) to the analyzed sample. Content of each component in CGM and extended uncertainty of its content

(к = 2) are provided in Tables 3 and 4. Type of graduation dependence of gas analyzer (1) and chromatograph (2) 1) X=9954,2*Y R2 = 0,9996 2) X=950,49*Y + 0,3644 R2 = 1,0000 Where: Y – value of equipment response. X – result of observation over the carbon oxide content. R2 – value of the approximation reliability.

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Table 3 – Calibration gas mixtures for gas analyzer GIAM-15m Vessel number,

molume, material, preparation date

Component Content,

x (mol/mol)

Extended uncertainty, U(x),

(mol/mol) СО 0,0000911 0,0000006 N2 0,9991059 0,0000028

5145, 4 dm3, aluminum 17.12.2007. Ar+O2 0,0007979 0,0000028

СО 0,0001116 0,0000006 N2 0,9990840 0,0000028

5141, 4 dm3, aluminum 18.12.2007. Ar+O2 0,0007985 0,0000028

СО 0,0001920 0,0000002 N2 0,9990050 0,0000030

3359, 4 dm3, steel 20.11.2007. Ar+O2 0,0007980 0,0000028

Table 4 – Calibration gas mixtures for chromatograph Vessel number,

molume, material, preparation date

Component Content,

x (mol/mol)

Extended uncertainty, U(x),

(mol/mol) СО 0,0009227 0,0000020 N2 0,9982740 0,0000026 26606, 4 dm3,

steel, 17.12.2007. Ar+O2 0,0007978 0,0000028 СО 0,0011377 0,0000020 N2 0,9980575 0,0000026

26673, 4 dm3, steel, 18.12.2007. Ar+O2 0,0007984 0,0000027

СО 0,0004820 0,0000039 N2 0,9987131 0,0000030 2813, 4 dm3, steel,

01.03.2007. Ar+O2 0,0007985 0,0000028 Number of observations for each CGM for equipment calibration – 6. Number of observations of each gas mixture standard sample during

measurement of the carbon oxide content – 5. Calculation of values for the content of determined components in compared

samples and of uncertainty of these values was performed according the data processing program B_LEAST, recommended by ISO 6143.

Final component content was determined as average from the measurement results.

Results are provided in the Tables 1 and 2 of the following sections: «Results of experimental research» and «Final results». 4. Sample handling The laboratory possesses the following equipment: conditioner to maintain the set temperature and humidity, as well as the following ancillary measurement

26

instruments: thermometer, psychometric hygrometer, barometer – to control temperature, humidity and atmospheric pressure in the premises.

Vessel with the sample for comparisons was stored in the laboratory from the moment of it delivery in Minsk. Vessels with CGM and SGM are stored on shelves in horizontal position, and during measurements they are turned in vertical position.

To the analysis the sample is delivered through the fine adjustment valve (VTR – 1). Connections "vessel –VTR", "VTR – tube", "tube – dosator" – are metallic and made in the form of adapters with spherical ends and buhes.

5. Calculation of uncertainty Results of calculation of the uncertainty of measurements of the CO content

in SGM are presented in the Tables 1 and 2 of the Section «Final results». Data for uncertainty assessment are provided in the Tables 5 and 6.

Table 5 – Assessment of the uncertainty of SGM measurements (0,1 mmol/mol СО in nitrogen) on gas analyzer GIAM -15m. Vessel number: D 95 5061

Uncertainty source

Xj

Assessment

xj

Expected distribution

Standard uncertainty

u(xj), % rel.

Sensitivity

coefficient, cj

Contribution to standard uncertainty,

uj(y), % rel.

Calibration of gas analyzer

Ucal normal 0,60 1 0,60

Temperature change

Utemp rectangular 0,20 1 0,20

Atmospheric pressure change

Uatm.pre

s rectangular 0,28 1 0,28

Standard deviation of observations

Useries normal 0,21 1 0,21

Standard deviation of 3 measurements

uA normal 0,07 1 0,07

Relative total standard uncertainty 0,73 Coverage factor^ k=2 Extended uncertainty: 0,015 * 10-4 mol/mol

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Table 6 – Assessment of the uncertainty of SGM measurements (1 mmol/mol СО in nitrogen) on chromatograph «НР - 6890N». Vessel number: D 20 0381

Coverage factor^ k=2 Extended uncertainty: 0.093 * 10-4 mol/mol Total standard measurement uncertainty was calculated according to the formula:

22

.222)( Адаватмтемсериикал uuuuuxu ++++= ,

(1)

where ucal – uncertainty of the component content, related to the uncertainty of chromatograph calibration;

utemp – uncertainty of the component content, related to the changes of environment temperature; uatm, pres – uncertainty of the component content, related to the atmospheric pressure change; u A – standard uncertainty of the N measurements. Scientist, keeper of the standard NE RB 13-04 V.N. Ananyin

Uncertainty source

Xj

Assessment

xj

Expected distribution

Standard uncertainty

u(xj), % rel.

Sensitivity

coefficient, cj

Contribution to standard

uncertainty, uj(y), % rel.

Calibration of chromatograph

Ucal normal 0,1 1 0,1

Temperature change

Utemp rectangular 0,2 1 0,2

Atmospheric pressure change

Uatm.pre

s rectangular 0,28 1 0,28

Standard deviation of observations

Useries normal 0,24 1 0,24

Standard deviation of 4 measurements

uA normal 0,17 1 0,17

Relative total standard uncertainty 0,46

useries – uncertainty of the component content, Standard deviation of 5 observations

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