CCQM-K91, SIM.QM-K91 and APMP.QM-K91

MEASURAND : Acidity function at zero chloride molality, pa0, of an unknown phthalate buffer
Sample: Potassium hydrogen phthalate, KHC8H4O4
Measurements at 15 °C

NOMINAL VALUE : pH ~ 4.01 at 25 °C

Degrees of equivalence, Di and expanded uncertainty Ui (k = 2) 

pH ~ 4.01 at 15 °C
Di 
Participating institutes

CCQM-K91, SIM.QM-K91 and APMP.QM-K91

MEASURAND : Acidity function at zero chloride molality, pa0, of an unknown phthalate buffer
Sample: Potassium hydrogen phthalate, KHC8H4O4
Measurements at 25 °C

NOMINAL VALUE : pH ~ 4.01 at 25 °C

Degrees of equivalence, Di and expanded uncertainty Ui (k = 2) 

pH ~ 4.01 at 25 °C
Di 
Participating institutes

CCQM-K91, SIM.QM-K91 and APMP.QM-K91

MEASURAND : Acidity function at zero chloride molality, pa0, of an unknown phthalate buffer
Sample: Potassium hydrogen phthalate, KHC8H4O4
Measurements at 37 °C

NOMINAL VALUE : pH ~ 4.01 at 25 °C

Degrees of equivalence, Di and expanded uncertainty Ui (k = 2)

pH ~ 4.01 at 37 °C
Di 
Participating institutes

CCQM-K91, SIM.QM-K91 and APMP.QM-K91

MEASURAND : Acidity function at zero chloride molality, pa0, of an unknown phthalate buffer
Sample: Potassium hydrogen phthalate, KHC8H4O4
Measurements at 15 °C

NOMINAL VALUE : pH ~ 4.01 at 25 °C

Degrees of equivalence, Di and expanded uncertainty Ui (k = 2) 

LABi Di Uneg,i Upos,i
dimensionless
dimensionless
dimensionless
BIM (revised) -0.0036 0.0081
BIM (original) -0.0102 0.0081
INMETRO -0.0022 0.0032
DFM 0.0004 0.0016
PTB 0.0010 0.0026
LNE -0.0018 0.0045
NMIJ 0.0001 0.0026
MKEH -0.0006 0.0030
CENAM -0.0045 0.0023
GUM -0.0001 0.0030
VNIIFTRI 0.0003 0.0061
SMU 0.0009 0.0023
NIMT -0.0038 0.0051
NIST 0.0014 0.0016
INDECOPI 0.0024 0.0041
BIM -0.0019 0.0079
INDECOPI 0.0004 0.0076
NIMT -0.0111 0.0096
SE "Ukrmetrteststandard" -0.0320 0.0088
LATU 0.0000 0.0122
RCChem-LIPI -0.0003 0.0032
VMI-STAMEQ 0.0127 0.0106
CMI -0.0013 0.0042
VNIIFTRI -0.0025 0.0046
UME 0.0218 0.0060
CENAM -0.0045 0.0142
INACAL -0.0005 0.0040
NMIM -0.0020 0.0064
BelGIM -0.0103 0.0068
GL -0.0003 0.0144
Participating institutes
CCQM-K91
SIM.QM-K91
APMP.QM-K91

CCQM-K91, SIM.QM-K91 and APMP.QM-K91

MEASURAND : Acidity function at zero chloride molality, pa0, of an unknown phthalate buffer
Sample: Potassium hydrogen phthalate, KHC8H4O4
Measurements at 25 °C

NOMINAL VALUE : pH ~ 4.01 at 25 °C

Degrees of equivalence, Di and expanded uncertainty Ui (k = 2)

LABi Di Uneg,i Upos,i
dimensionless
dimensionless
dimensionless
BIM (revised) -0.0028 0.0080
BIM (original) -0.0104 0.0080
INMETRO -0.0017 0.0024
DFM 0.0005 0.0013
PTB 0.0006 0.0025
LNE -0.0014 0.0037
NMIJ -0.0004 0.0025
MKEH 0.0012 0.0029
CENAM -0.0031 0.0024
GUM -0.0009 0.0033
VNIIFTRI 0.0007 0.0074
SMU 0.0011 0.0022
NIMT -0.0052 0.0051
NIST 0.0011 0.0018
INDECOPI -0.0012 0.0041
BIM -0.0019 0.0055
IBMETRO -0.0045 0.0054
INM (CO) 0.0008 0.0063
INDECOPI -0.0020 0.0047
NIMT -0.0119 0.0051
SE "Ukrmetrteststandard" -0.0347 0.0052
LATU -0.0004 0.0106
RCChem-LIPI -0.0015 0.0030
VMI-STAMEQ 0.0204 0.0104
CMI 0.0021 0.0076
VNIIFTRI 0.0001 0.0046
UME 0.0217 0.0038
CENAM -0.0094 0.0098
INACAL -0.0019 0.0038
NMIM* 0.0009 0.0068
BelGIM -0.0073 0.0048
GL -0.0015 0.0132
Participating institutes
CCQM-K91
SIM.QM-K91
APMP.QM-K91

CCQM-K91, SIM.QM-K91 and APMP.QM-K91

MEASURAND : Acidity function at zero chloride molality, pa0, of an unknown phthalate buffer
Sample: Potassium hydrogen phthalate, KHC8H4O4
Measurements at 37 °C

NOMINAL VALUE : pH ~ 4.01 at 25 °C

Degrees of equivalence, Di and expanded uncertainty Ui (k = 2)

LABi Di Uneg,i Upos,i
dimensionless
dimensionless
dimensionless
BIM (revised) -0.0014 0.0081
BIM (original) -0.0089 0.0081
INMETRO -0.0016 0.0025
DFM 0.0010 0.0014
PTB -0.0004 0.0026
LNE -0.0035 0.0041
NMIJ 0.0004 0.0031
MKEH -0.0045 0.0061
CENAM -0.0014 0.0026
GUM -0.0031 0.0029
VNIIFTRI -0.0010 0.0081
SMU 0.0015 0.0022
NIMT -0.0033 0.0081
NIST 0.0006 0.0039
INDECOPI -0.0012 0.0041
BIM -0.0039 0.0040
INDECOPI -0.0038 0.0032
NIMT 0.0235 0.0077
SE "Ukrmetrteststandard" -0.0461 0.0040
LATU -0.0015 0.0101
RCChem-LIPI -0.0002 0.0032
VMI-STAMEQ 0.0858 0.0104
CMI -0.0025 0.0046
VNIIFTRI 0.0013 0.0044
UME 0.0198 0.0062
CENAM 0.0048 0.0170
INACAL 0.0000 0.0048
NMIM* -0.0154 0.0062
BelGIM -0.0109 0.0070
GL -0.0022 0.0118
Participating institutes
CCQM-K91
SIM.QM-K91
APMP.QM-K91
Comparison
Comparison close
CC comparison
Linked comparison
SIM.QM-K91
Metrology area, Sub-field Chemistry and Biology, Electrochemistry
Description pH measurement of an unknown phthalate buffer
Time of measurements 2014
Status Approved for equivalence
Final Reports of the comparisons
Measurand pH ~ 4.01 at temperature 25 °C
Parameters Temperature: 15 °C, 25 °C and 37 °C
Transfer device A phthalate buffer solution
Comparison type Key Comparison
Consultative Committee CCQM (Consultative Committee for Amount of Substance)
Conducted by SIM (Inter-American Metrology System)
Comments

 

 

Results published on 26 June 2015

SIM.QM-K91 and APMP.QM-K91 results are linked to those of CCQM-K91

pH determination of a phthalate buffer

 

 

Pilot institute INMETRO
Instituto Nacional de Metrologia, Qualidade e Tecnologia
Brazil
Contact person F. Barbieri Gonzaga

+55 21 2679 9134
First Name Last Name
wwww@ww.www +356719836 Institute 1 Institute 1 Khmelnitskiy
Pilot laboratory
INMETRO

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

BIM

Bulgarian Institute of Metrology, Bulgaria, 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

INM (CO)

Instituto Nacional de Metrología de Colombia, Colombia, SIM

LATU

Laboratorio Tecnologico del Uruguay, Uruguay, SIM

NIMT

National Institute of Metrology (Thailand), Thailand, APMP

NIST

National Institute of Standards and Technology, United States, SIM

SE "Ukrmetrteststandard"

State Enterprise "Ukrmetrteststandard", Ukraine, EURAMET

CCQM-K91, SIM.QM-K91 and APMP.QM-K91

MEASURAND : Acidity function at zero chloride molality, pa0, of an unknown phthalate buffer
Sample: Potassium hydrogen phthalate, KHC8H4O4
Measurements at 15 °C

NOMINAL VALUE : pH ~ 4.01 at 25 °C

  • Key comparison CCQM-K91
The key comparison reference value, xR, is calculated as the weighted mean of the participants' results excluding those from BIM, INDECOPI, UME, and, SE "Ukrmetrteststandard". The standard uncertainty, uR, of xR is calculated according to the external consistency method (see page 15 of the Final Report).

pa0R = 4.0853 and UR = 2uR = 0.0011

The degree of equivalence of laboratory i with respect to the key comparison reference value is given by a pair of terms: Di = (xi - xR) and Ui, its expanded uncertainty (k = 2),
Ui = 2(ui2 + uR2)1/2.

There are no pair-wise degrees of equivalence computed for this key comparison.
  • Linking key comparison SIM.QM-K91

The common participation of INMETRO and NIST in two key comparisons makes it possible to compute the linkage of the results, as explained on pages 10 and 11 of the SIM.QM-K91 Final Report.

  • Linking key comparison APMP.QM-K91

The common participation of NMIJ and PTB in two key comparisons makes it possible to compute the linkage of the results.

CCQM-K91, SIM.QM-K91 and APMP.QM-K91

MEASURAND : Acidity function at zero chloride molality, pa0, of an unknown phthalate buffer
Sample: Potassium hydrogen phthalate, KHC8H4O4
Measurements at 25 °C

NOMINAL VALUE : pH ~ 4.01 at 25 °C

  • Key comparison CCQM-K91
The key comparison reference value, xR, is calculated as the weighted mean of the participants' results excluding those from BIM, Indecopi, UME, and, SE "Ukrmetrteststandard". The standard uncertainty, uR, of xR is calculated according to the external consistency method (see page 15 of the Final Report).

pa0R = 4.0935 and UR = 2uR = 0.00083

The degree of equivalence of laboratory i with respect to the key comparison reference value is given by a pair of terms: Di = (xi - xR) and Ui, its expanded uncertainty (k = 2),
Ui = 2(ui2 + uR2)1/2.

There are no pair-wise degrees of equivalence computed for this key comparison.
  • Linking key comparison SIM.QM-K91

The common participation of INMETRO and NIST in two key comparisons makes it possible to compute the linkage of the results, as explained on pages 10 and 11 of the SIM.QM-K91 Final Report.

  • Linking key comparison APMP.QM-K91

The common participation of NMIJ and PTB in two key comparisons makes it possible to compute the linkage of the results.

CCQM-K91, SIM.QM-K91 and APMP.QM-K91

MEASURAND : Acidity function at zero chloride molality, pa0, of an unknown phthalate buffer
Sample: Potassium hydrogen phthalate, KHC8H4O4
Measurements at 37 °C

NOMINAL VALUE : pH ~ 4.01 at 25 °C

  • Key comparison CCQM-K91
The key comparison reference value, xR, is calculated as the weighted mean of the participants' results excluding those from BIM, Indecopi, UME, and, SE "Ukrmetrteststandard". The standard uncertainty, uR, of xR is calculated according to the external consistency method (see page 15 of the Final Report).

pa0R = 4.1147 and UR = 2uR = 0.00092

The degree of equivalence of laboratory i with respect to the key comparison reference value is given by a pair of terms: Di = (xi - xR) and Ui, its expanded uncertainty (k = 2),
Ui = 2(ui2 + uR2)1/2.

There are no pair-wise degrees of equivalence computed for this key comparison.
  • Linking key comparison SIM.QM-K91

The common participation of INMETRO and NIST in two key comparisons makes it possible to compute the linkage of the results, as explained on pages 10 and 11 of the SIM.QM-K91 Final Report.

  • Linking key comparison APMP.QM-K91

The common participation of NMIJ and PTB in two key comparisons makes it possible to compute the linkage of the results.

CCQM-K91, SIM.QM-K91 and APMP.QM-K91

MEASURAND : Acidity function at zero chloride molality, pa0, of an unknown phthalate buffer
Sample: Potassium hydrogen phthalate, KHC8H4O4
Measurements at 15 °C

NOMINAL VALUE : pH ~ 4.01 at 25 °C

  • Key comparison CCQM-K91

xi : result of measurement carried out by laboratory i
U
Labi : expanded uncertainty (k = 2) of xi; ULabi = 2ui

* BIM observed a calculation error in the standard potential E0 and sent revised pa0 values one month after the comparison deadline.
**INDECOPI used a secondary measurement method.
***UME and SE "Ukrmetrteststandard" reported problems with their measurements (see page 9 of the Final Report).

  • Key comparison SIM.QM-K91

xi : result of measurement carried out by laboratory i
u
i : combined standard uncertainty of xi


  • Key comparison APMP.QM-K91

xi : result of measurement carried out by laboratory i
u
i : combined standard uncertainty of xi


NMIM, formerly known as NRL-SIRIM

CCQM-K91, SIM.QM-K91 and APMP.QM-K91

MEASURAND : Acidity function at zero chloride molality, pa0, of an unknown phthalate buffer
Sample: Potassium hydrogen phthalate, KHC8H4O4
Measurements at 25 °C

NOMINAL VALUE : pH ~ 4.01 at 25 °C

  • Key comparison CCQM-K91

xi : result of measurement carried out by laboratory i
U
Labi : expanded uncertainty (k = 2) of xi; ULabi = 2ui

* BIM observed a calculation error in the standard potential E0 and sent revised pa0 values one month after the comparison deadline.
**INDECOPI used a secondary measurement method.
***UME and SE "Ukrmetrteststandard" reported problems with their measurements (see page 9 of the Final Report).

  • Key comparison SIM.QM-K91

xi : result of measurement carried out by laboratory i
u
i : combined standard uncertainty of xi

ul>

  • Key comparison APMP.QM-K91

xi : result of measurement carried out by laboratory i
u
i : combined standard uncertainty of xi

NMIM, formerly known as NRL-SIRIM

CCQM-K91, SIM.QM-K91 and APMP.QM-K91

MEASURAND : Acidity function at zero chloride molality, pa0, of an unknown phthalate buffer
Sample: Potassium hydrogen phthalate, KHC8H4O4
Measurements at 37 °C

NOMINAL VALUE : pH ~ 4.01 at 25 °C

  • Key comparison CCQM-K91

xi : result of measurement carried out by laboratory i
U
Labi : expanded uncertainty (k = 2) of xi; ULabi = 2ui

* BIM observed a calculation error in the standard potential E0 and sent revised pa0 values one month after the comparison deadline.
**Indecopi used a secondary measurement method.
***UME and SE "Ukrmetrteststandard" reported problems with their measurements (see page 9 of the Final Report).

  • Key comparison SIM.QM-K91

xi : result of measurement carried out by laboratory i
u
i : combined standard uncertainty of xi

  • Key comparison SIM.QM-K91

xi : result of measurement carried out by laboratory i
u
i : combined standard uncertainty of xi

NMIM, formerly known as NRL-SIRIM