Comparison Display

CCQM-K99 and CCQM-K99.1

MEASURAND pH value of an unknown phosphate buffer

NOMINAL VALUE pH = 7.5

Degrees of equivalence represented by D_i = (x_i - x_R) and its expanded uncertainty U_i at a 95 % level of confidence.

pH at 15 °C

D_i

Participating institutes

Enlarged graph

CCQM-K99_T15_Graph

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CCQM-K99 and CCQM-K99.1

MEASURAND pH value of an unknown phosphate buffer

NOMINAL VALUE pH = 7.5

Degrees of equivalence represented by D_i = (x_i - x_R) and its expanded uncertainty U_i at a 95 % level of confidence.

pH at 25 °C

D_i

Participating institutes

Enlarged graph

CCQM-K99_T25_Graph

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CCQM-K99 and CCQM-K99.1

MEASURAND pH value of an unknown phosphate buffer

NOMINAL VALUE pH = 7.5

Degrees of equivalence represented by D_i = (x_i - x_R) and its expanded uncertainty U_i at a 95 % level of confidence.

pH at 37 °C

D_i

Participating institutes

Enlarged graph

CCQM-K99_T37_Graph

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CCQM-K99 and CCQM-K99.1

MEASURAND pH value of an unknown phosphate buffer

NOMINAL VALUE pH = 7.5

Degrees of equivalence represented by D_i = (x_i - x_R) and its expanded uncertainty U_i at a 95 % level of confidence.

LAB_i	D_i	U_neg,i	U_pos,i
	dimensionless	dimensionless	dimensionless
BIM	-0.001	0.004
CENAM	0.000	0.004
CMI	0.002	0.003
DFM	0.000	0.002
GUM	-0.009	0.003
INDECOPI	-0.002	0.004
INMETRO	0.002	0.003
MKEH	0.000	0.006
NIMT	-0.055	0.039
NIST	0.002	0.002
NMIJ	0.000	0.003
PTB	-0.001	0.003
SMU	-0.001	0.004
UME	-0.022	0.002
SE "Ukrmetrteststandard"	0.012	0.006
VNIIFTRI	-0.004	0.004
KRISS	-0.001	0.004

Participating institutes

CCQM-K99

CCQM-K99.1

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CCQM-K99 and CCQM-K99.1

MEASURAND pH value of an unknown phosphate buffer

NOMINAL VALUE pH = 7.5

Degrees of equivalence represented by D_i = (x_i - x_R) and its expanded uncertainty U_i at a 95 % level of confidence.

LAB_i	D_i	U_neg,i	U_pos,i
	dimensionless	dimensionless	dimensionless
BIM	-0.002	0.004
CENAM	-0.001	0.006
CMI	0.004	0.003
DFM	-0.001	0.002
GUM	-0.007	0.003
IBMETRO	0.003	0.010
INDECOPI	-0.004	0.004
INMETRO	0.001	0.003
LATU	-0.004	0.010
MKEH	-0.002	0.007
NIMT	-0.057	0.029
NIST	0.001	0.002
NMIJ	-0.001	0.002
PTB	-0.001	0.003
SMU	-0.003	0.003
UME	0.005	0.002
SE "Ukrmetrteststandard"	0.005	0.004
VNIIFTRI	-0.006	0.004
KRISS	-0.002	0.004

Participating institutes

CCQM-K99

CCQM-K99.1

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CCQM-K99 and CCQM-K99.1

MEASURAND pH value of an unknown phosphate buffer

NOMINAL VALUE pH = 7.5

Degrees of equivalence represented by D_i = (x_i - x_R) and its expanded uncertainty U_i at a 95 % level of confidence.

LAB_i	D_i	U_neg,i	U_pos,i
	dimensionless	dimensionless	dimensionless
BIM	-0.006	0.004
CENAM	-0.004	0.005
CMI	-0.006	0.004
DFM	0.001	0.002
GUM	-0.010	0.004
INDECOPI	0.000	0.004
INMETRO	-0.001	0.005
LATU	0.002	0.010
MKEH	-0.004	0.007
NIMT	-0.053	0.022
NIST	0.002	0.002
NMIJ	0.001	0.003
PTB	0.001	0.003
SMU	-0.001	0.004
UME	-0.020	0.003
SE "Ukrmetrteststandard"	0.004	0.005
VNIIFTRI	-0.004	0.005
KRISS	0.001	0.004

Participating institutes

CCQM-K99

CCQM-K99.1

Comparison

Comparison close

CCQM-K99

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Information & contact
Participants

Metrology area, Sub-field	Chemistry and Biology, Electrochemistry
Description	pH of phosphate buffer
Time of measurements	2014
Status	Approved for equivalence

Final Reports of the comparisons	CCQM-K99 Final Report, 18 pp.
Measurand	pH ~ 7.5
Transfer device	Dedicated samples

Comparison type	Key Comparison
Consultative Committee	CCQM (Consultative Committee for Amount of Substance)
Conducted by	CCQM (Consultative Committee for Amount of Substance)
Comments	Results published on 4 January 2016 pH of an unknown phosphate buffer
Pilot institute	PTB Physikalisch-Technische Bundesanstalt Germany
Contact person	Frank Bastkowski

Pilot laboratory
PTB	Physikalisch-Technische Bundesanstalt, Germany, EURAMET

BIM	Bulgarian Institute of Metrology, Bulgaria, EURAMET

CENAM

Centro Nacional de Metrologia, Mexico, SIM

CMI	Czech Metrology Institute, Czechia, EURAMET

DFM	Danish Fundamental Metrology A/S, Denmark, EURAMET

GUM	Glowny Urzad Miar, Central Office of Measures, Poland, EURAMET

IBMETRO

Instituto Boliviano de Metrología, Bolivia, SIM

INDECOPI

Instituto Nacional de Defensa de la Competencia y de la Protección de la Propiedad Intelectual, Peru, SIM

INMETRO

Instituto Nacional de Metrologia, Qualidade e Tecnologia, Brazil, SIM

LATU	Laboratorio Tecnologico del Uruguay, Uruguay, SIM

MKEH	Hungarian Trade Licensing Office; now BFKH, Hungary, EURAMET

NIMT	National Institute of Metrology (Thailand), Thailand, APMP

NIST	National Institute of Standards and Technology, United States, SIM

NMIJ AIST

National Metrology Institute of Japan, Japan, APMP

SE "Ukrmetrteststandard"

State Enterprise "Ukrmetrteststandard", Ukraine, EURAMET

SMU	Slovensky Metrologicky Ustav, Slovakia, EURAMET

UME	TÜBITAK Ulusal Metroloji Enstitüsü, Türkiye, EURAMET

VNIIFTRI

Institute of Physical Technical and Radiotechnical Measurements, Rosstandart, Russian Federation, COOMET

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CCQM-K99 and CCQM-K99.1

MEASURAND pH value of an unknown phosphate buffer

NOMINAL VALUE pH = 7.5

The key comparison reference value x_R and its associated standard uncertainty u_R is obtained by calculating the weigthted mean including the institutes using primary standards for which the results passed a previously defined consistancy filter.

x_R = 7.5561 u_R = 0.0009

The degree of equivalence of laboratory i relative to the key comparison reference value x_R is given by a pair of terms:

D_i = (x_i - x_R) and its expanded uncertainty U_i at a 95 % level of confidence where U_i = 2 ( (1 − 2w_i) u_i² + u_R²)^1/2 where w_i represents the weight of laboratory i.

Linking CCQM-K99.1 to CCQM-K99

PTB provides the link between the key comparison CCQM-K99 and CCQM-K99.1, having participated in both comparisons. The linking process is described in Section 9 of the CCQM-K99.1 Final report.

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CCQM-K99 and CCQM-K99.1

MEASURAND pH value of an unknown phosphate buffer

NOMINAL VALUE pH = 7.5

x_R = 7.5246 u_R = 0.0008

The degree of equivalence of laboratory i relative to the key comparison reference value x_R is given by a pair of terms:

D_i = (x_i - x_R) and its expanded uncertainty U_i at a 95 % level of confidence where U_i = 2 ( (1 − 2w_i) u_i² + u_R²)^1/2 where w_i represents the weight of laboratory i.

Linking CCQM-K99.1 to CCQM-K99

PTB provides the link between the key comparison CCQM-K99 and CCQM-K99.1, having participated in both comparisons. The linking process is described in Section 9 of the CCQM-K99.1 Final report.

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CCQM-K99 and CCQM-K99.1

MEASURAND pH value of an unknown phosphate buffer

NOMINAL VALUE pH = 7.5

x_R = 7.5013 u_R = 0.0009

The degree of equivalence of laboratory i relative to the key comparison reference value x_R is given by a pair of terms:

D_i = (x_i - x_R) and its expanded uncertainty U_i at a 95 % level of confidence where U_i = 2 ( (1 − 2w_i) u_i² + u_R²)^1/2 where w_i represents the weight of laboratory i.

Linking CCQM-K99.1 to CCQM-K99

PTB provides the link between the key comparison CCQM-K99 and CCQM-K99.1, having participated in both comparisons. The linking process is described in Section 9 of the CCQM-K99.1 Final report.

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CCQM-K99 and CCQM-K99.1

MEASURAND pH value of an unknown phosphate buffer

NOMINAL VALUE pH = 7.5

x_i measurement value submitted by institute i, Lab_i

u_i combined standard uncertainty of x_i

CCQM-K99

Lab_i	x_i	u_i
Lab_i	x_i	u_i
BIM	7.5553	0.0020
CENAM	7.5561	0.0016
CMI	7.5585	0.0013
DFM	7.5563	0.0008
GUM	7.5474	0.0013
INDECOPI	7.5542	0.0020
INMETRO	7.5582	0.0013
MKEH	7.5558	0.0030
NIMT	7.5006	0.0197
NIST	7.5578	0.0008
NMIJ	7.5561	0.0010
PTB	7.5553	0.0011
SMU	7.5554	0.0016
UME	7.5337	0.0010
SE "Ukrmetrteststandard"	7.5683	0.0028
VNIIFTRI	7.5520	0.0020

CCQM-K99.1

Lab_i	x_i	u_i

KRISS	7.3265	0.0013

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CCQM-K99 and CCQM-K99.1

MEASURAND pH value of an unknown phosphate buffer

NOMINAL VALUE pH = 7.5

x_i measurement value submitted by institute i, Lab_i

u_i combined standard uncertainty of x_i

CCQM-K99

Lab_i	x_i	u_i
Lab_i	x_i	u_i
BIM	7.5228	0.0020
CENAM	7.5239	0.0027
CMI	7.5287	0.0013
DFM	7.5232	0.0008
GUM	7.5178	0.0014
IBMETRO	7.5276	0.0050
INDECOPI	7.5209	0.0020
INMETRO	7.5255	0.0013
LATU	7.5206	0.0050
MKEH	7.5226	0.0033
NIMT	7.4679	0.0143
NIST	7.5255	0.0008
NMIJ	7.5236	0.0010
PTB	7.5235	0.0011
SMU	7.5220	0.0015
UME	7.5291	0.0010
SE "Ukrmetrteststandard"	7.5295	0.0021
VNIIFTRI	7.5190	0.0021

CCQM-K99.1

Lab_i	x_i	u_i

KRISS	7.2936	0.0014

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CCQM-K99 and CCQM-K99.1

MEASURAND pH value of an unknown phosphate buffer

NOMINAL VALUE pH = 7.5

x_i measurement value submitted by institute i, Lab_i

u_i combined standard uncertainty of x_i

CCQM-K99

Lab_i	x_i	u_i
Lab_i	x_i	u_i
BIM	7.4951	0.0020
CENAM	7.4973	0.0024
CMI	7.4954	0.0020
DFM	7.5021	0.0008
GUM	7.4917	0.0016
INDECOPI	7.5014	0.0020
INMETRO	7.5006	0.0022
LATU	7.5029	0.0050
MKEH	7.4973	0.0034
NIMT	7.4482	0.0110
NIST	7.5036	0.0008
NMIJ	7.5025	0.0010
PTB	7.5027	0.0011
SMU	7.5005	0.0019
UME	7.4812	0.0010
SE "Ukrmetrteststandard"	7.5055	0.0021
VNIIFTRI	7.4970	0.0023

CCQM-K99.1

Lab_i	x_i	u_i

KRISS	7.2725	0.0014

KCDB

CIPM MRA

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Key and supplementary comparisons - Print out