CCQM-K17 and EUROMET.QM-K17
MEASURAND : pH value of phthalate buffer
Sample: Potassium hydrogen phthalate, KHC8H4O4
Measurements at 15 °C
NOMINAL VALUE : pH = 4.0 at 25 °C
Degrees of equivalence Di and expanded uncertainty Ui (k = 2)
.gif)
Red diamonds: participants in CCQM-K17
Green triangle: participant in EUROMET.QM-K17
CCQM-K17 and EUROMET.QM-K17
MEASURAND : pH value of phthalate buffer
Sample: Potassium hydrogen phthalate, KHC8H4O4
Measurements at 25 °C
NOMINAL VALUE : pH = 4.0 at 25 °C
Degrees of equivalence Di and expanded uncertainty Ui (k = 2)
.gif)
Red diamonds: participants in CCQM-K17
Green triangle: participant in EUROMET.QM-K17
CCQM-K17 and EUROMET.QM-K17
MEASURAND : pH value of phthalate buffer
Sample: Potassium hydrogen phthalate, KHC8H4O4
Measurements at 37 °C
NOMINAL VALUE : pH = 4.0 at 25 °C
Degrees of equivalence Di and expanded uncertainty Ui (k = 2)
.gif)
Red diamonds: participants in CCQM-K17
Green triangle: participant in EUROMET.QM-K17
CCQM-K17 and EUROMET.QM-K17
MEASURAND : pH value of phthalate buffer
Sample: Potassium hydrogen phthalate, KHC8H4O4
Measurements at 15 °C
NOMINAL VALUE : pH = 4.0 at 25 °C
Degrees of equivalence Di and expanded uncertainty Ui (k = 2)
.gif)
BNM-LNE*: participant in EUROMET.QM-K17
CCQM-K17 and EUROMET.QM-K17
MEASURAND : pH value of phthalate buffer
Sample: Potassium hydrogen phthalate, KHC8H4O4
Measurements at 25 °C
NOMINAL VALUE : pH = 4.0 at 25 °C
Degrees of equivalence Di and expanded uncertainty Ui (k = 2)
.gif)
BNM-LNE*: participant in EUROMET.QM-K17
CCQM-K17 and EUROMET.QM-K17
MEASURAND : pH value of phthalate buffer
Sample: Potassium hydrogen phthalate, KHC8H4O4
Measurements at 37 °C
NOMINAL VALUE : pH = 4.0 at 25 °C
Degrees of equivalence Di and expanded uncertainty Ui (k = 2)
.gif)
BNM-LNE*: participant in EUROMET.QM-K17
| Metrology area, Sub-field | Chemistry and Biology, Electrochemistry |
| Description | pH measurement of phthalate buffer solutions |
| Time of measurements | 2003 |
| Status | Approved for equivalence |
| Final Reports of the comparisons | |
| Measurand | pH 4.1 at temperature 25 °C |
| Parameters | Temperature: 15 °C, 25 °C and 37 °C |
| Transfer device | A phthalate buffer, containing potassium hydrogen phthalate at a molality of 0.05 mol/kg |
| Comparison type | Key Comparison |
| Consultative Committee | CCQM (Consultative Committee for Amount of Substance) |
| Conducted by | EURAMET (European Association of National Metrology Institutes) |
| RMO Internal Identifier | EUROMET Project No 696 |
| Comments | EUROMET.QM-K17 results are linked to those of CCQM-K17. CCQM-K17 results were published on 8 September 2003, and EUROMET.QM-K17 results on 28 February 2005. pH determination of a phthalate buffer at temperatures ranging from 15 °C to 37 °C. |
| Pilot institute |
PTB
Physikalisch-Technische Bundesanstalt Germany |
| Contact person | P. Spitzer +49 (0) 531 592 3130 |
This page proposes print-out on A4 paper (portrait) of the comparison details (best printed out using a black and white printer).
Please, select items to be printed out, then click on "OK" :
CCQM-K17 and EUROMET.QM-K17
MEASURAND : pH value of phthalate buffer
Sample: Potassium hydrogen phthalate, KHC8H4O4
Measurements at 15 °C
NOMINAL VALUE : pH = 4.0 at 25 °C
|
The key comparison reference value, pHR, is obtained as the variance-weighted mean of the results from the participants. The standard uncertainty, uR, of pHR is calculated according to the external consistency concept (see page 8 of CCQM-K17 Final Report). pHR = 4.0093 and uR = 0.00089 |
| The degree of equivalence of each laboratory with respect to the key comparison reference value is given by a pair of terms: Di = (pHi - pHR) and Ui, its expanded uncertainty (k = 2), Ui = 2(ui2 + uR2)1/2. Note that this gives a conservative estimate of Ui. |
| The degree of equivalence between two laboratories may be calculated using the following pair of terms: Dij = Di - Dj = pHi - pHj and Uij, its expanded uncertainty (k = 2), Uij = 2(ui2 + uj2)1/2. No numerical values of pair-wise degrees of equivalence are given. |
The PTB acted as pilot laboratory in both key comparisons.
To link the results obtained by the BNM-LNE in EUROMET.QM-K17 to CCQM-K17 the performance of PTB within its uncertainty is assumed to be similar in both comparisons. Therefore it is assumed that the bias between the PTB results and the key comparison reference value remains constant over both comparisons.
The degree of equivalence of the BNM-LNE with respect to the key comparison reference value is given by a pair of terms: Di and Ui, its expanded uncertainty
(k = 2), see equations 1 to 4 in the EUROMET.QM-K17 Final Report.
| The pair-wise degrees of equivalence involving the BNM-LNE are not calculated. |
CCQM-K17 and EUROMET.QM-K17
MEASURAND : pH value of phthalate buffer
Sample: Potassium hydrogen phthalate, KHC8H4O4
Measurements at 25 °C
NOMINAL VALUE : pH = 4.0 at 25 °C
|
The key comparison reference value, pHR, is obtained as the variance-weighted mean of the results from the participants. The standard uncertainty, uR, of pHR is calculated according to the external consistency concept (see page 8 of CCQM-K17 Final Report). pHR = 4.0156 and uR = 0.00109 |
| The degree of equivalence of each laboratory with respect to the key comparison reference value is given by a pair of terms: Di = (pHi - pHR) and Ui, its expanded uncertainty (k = 2), Ui = 2(ui2 + uR2)1/2. Note that this gives a conservative estimate of Ui. |
|
The degree of equivalence between two laboratories may be calculated using the following pair of terms: |
The PTB acted as pilot laboratory in both key comparisons.
To link the results obtained by the BNM-LNE in EUROMET.QM-K17 to CCQM-K17 the performance of PTB within its uncertainty is assumed to be similar in both comparisons. Therefore it is assumed that the bias between the PTB results and the key comparison reference value remains constant over both comparisons.
The degree of equivalence of the BNM-LNE with respect to the key comparison reference value is given by a pair of terms: Di and Ui, its expanded uncertainty
(k = 2), see equations 1 to 4 in the EUROMET.QM-K17 Final Report.
| The pair-wise degrees of equivalence involving the BNM-LNE are not calculated. |
CCQM-K17 and EUROMET.QM-K17
MEASURAND : pH value of phthalate buffer
Sample: Potassium hydrogen phthalate, KHC8H4O4
Measurements at 37 °C
NOMINAL VALUE : pH = 4.0 at 25 °C
|
The key comparison reference value, pHR, is obtained as the variance-weighted mean of the results from the participants. The standard uncertainty, uR, of pHR is calculated according to the external consistency concept (see page 8 of CCQM-K17 Final Report). pHR = 4.0343 and uR = 0.00125 |
| The degree of equivalence of each laboratory with respect to the key comparison reference value is given by a pair of terms: Di = (pHi - pHR) and Ui, its expanded uncertainty (k = 2), Ui = 2(ui2 + uR2)1/2. Note that this gives a conservative estimate of Ui. |
| The degree of equivalence between two laboratories may be calculated using the following pair of terms: Dij = Di - Dj = pHi - pHj and Uij, its expanded uncertainty (k = 2), Uij = 2(ui2 + uj2)1/2. No numerical values of pair-wise degrees of equivalence are given. |
The PTB acted as pilot laboratory in both key comparisons.
To link the results obtained by the BNM-LNE in EUROMET.QM-K17 to CCQM-K17 the performance of PTB within its uncertainty is assumed to be similar in both comparisons. Therefore it is assumed that the bias between the PTB results and the key comparison reference value remains constant over both comparisons.
The degree of equivalence of the BNM-LNE with respect to the key comparison reference value is given by a pair of terms: Di and Ui, its expanded uncertainty
(k = 2), see equations 1 to 4 in the EUROMET.QM-K17 Final Report.
| The pair-wise degrees of equivalence involving the BNM-LNE are not calculated. |
CCQM-K17 and EUROMET.QM-K17
MEASURAND : pH value of phthalate buffer
Sample: Potassium hydrogen phthalate, KHC8H4O4
Measurements at 15 °C
NOMINAL VALUE : pH = 4.0 at 25 °C
pHi : result of measurement carried out by laboratory i
ui : combined standard uncertainty (k = 1) of pHi
Ui : expanded uncertainty (k = 2) of pHi, Ui = 2ui
|
|
pHi | ui | Date of measurement |
| NRCCRM | 4.0070 | 0.0020 | Aug 01 |
| PTB | 4.0100 | 0.0011 | Jul 01 |
| Radiometer A/S | 4.0074 | 0.0008 | Jul 01 |
| KRISS | 4.0033 | 0.0015 | Jul 01 |
| NMIJ | 4.0024 | 0.0032 | Jul 01 |
| CENAM | 4.0020 | 0.0024 | Jul 01 |
| GUM | 4.0123 | 0.0015 | Jul 01 |
| VNIIFTRI | 4.0130 | 0.0013 | Jul 01 |
| SMU | 4.0095 | 0.0011 | Sep 01 |
| CMI | 4.0014 | 0.0017 | Sep 01 |
| NIST | 4.0108 | 0.0005 | Jul 01 |
|
|
pHi | Ui | Date of measurement |
| BNM-LNE | 3.9919 | 0.0024 | Feb 03 |
| PTB | 3.9985 | 0.0024 | Jan 03 |
CCQM-K17 and EUROMET.QM-K17
MEASURAND : pH value of phthalate buffer
Sample: Potassium hydrogen phthalate, KHC8H4O4
Measurements at 25 °C
NOMINAL VALUE : pH = 4.0 at 25 °C
pHi : result of measurement carried out by laboratory i
ui : combined standard uncertainty (k = 1) of pHi
Ui : expanded uncertainty (k = 2) of pHi, Ui = 2ui
|
|
pHi | ui | Date of measurement |
| NRCCRM | 4.0150 | 0.0020 | Aug 01 |
| PTB | 4.0168 | 0.0011 | Jul 01 |
| Radiometer A/S | 4.0150 | 0.0008 | Jul 01 |
| KRISS | 4.0104 | 0.0017 | Jul 01 |
| NMIJ | 4.0108 | 0.0030 | Jul 01 |
| CENAM | 4.0050 | 0.0022 | Jul 01 |
| GUM | 4.0183 | 0.0015 | Jul 01 |
| VNIIFTRI | 4.0193 | 0.0013 | Jul 01 |
| SMU | 4.0174 | 0.0011 | Sep 01 |
| CMI | 4.0050 | 0.0017 | Sep 01 |
| NIST | 4.0170 | 0.0006 | Jul 01 |
|
|
pHi | Ui | Date of measurement |
| BNM-LNE | 4.0002 | 0.0038 | Feb 03 |
| PTB | 4.0052 | 0.0024 | Jan 03 |
CCQM-K17 and EUROMET.QM-K17
MEASURAND : pH value of phthalate buffer
Sample: Potassium hydrogen phthalate, KHC8H4O4
Measurements at 37 °C
NOMINAL VALUE : pH = 4.0 at 25 °C
pHi : result of measurement carried out by laboratory i
ui : combined standard uncertainty (k = 1) of pHi
Ui : expanded uncertainty (k = 2) of pHi, Ui = 2ui
|
|
pHi | ui | Date of measurement |
| NRCCRM | 4.0370 | 0.0020 | Aug 01 |
| PTB | 4.0360 | 0.0015 | Jul 01 |
| Radiometer A/S | 4.0351 | 0.0008 | Jul 01 |
| KRISS | 4.0296 | 0.0017 | Jul 01 |
| NMIJ | 4.0261 | 0.0039 | Jul 01 |
| CENAM | 4.0290 | 0.0020 | Jul 01 |
| GUM | 4.0355 | 0.0015 | Jul 01 |
| VNIIFTRI | 4.0380 | 0.0013 | Jul 01 |
| SMU | 4.0397 | 0.0015 | Sep 01 |
| CMI | 4.0272 | 0.0011 | Sep 01 |
| NIST | 4.0371 | 0.0013 | Jul 01 |
|
|
pHi | Ui | Date of measurement |
| BNM-LNE | 4.0209 | 0.0046 | Feb 03 |
| PTB | 4.0225 | 0.0024 | Jan 03 |
