CCQM-K99
MEASURAND : pH value of an unknown phosphate buffer
Measurements at 15 °C, 25 °C, 37 °C. Optional: 5 °C and 50 °C.
NOMINAL VALUE : pH = 7.5
Degrees of equivalence Di and expanded uncertainty Ui (k = 2)
CCQM-K99
MEASURAND : pH value of an unknown phosphate buffer
Measurements at 15 °C, 25 °C, 37 °C. Optional: 5 °C and 50 °C.
NOMINAL VALUE : pH = 7.5
Degrees of equivalence Di and expanded uncertainty Ui (k = 2)
A printable Summary of Resuts is available in A4 format.
| Metrology area, Sub-field | Chemistry and Biology, Electrochemistry |
| Description | pH of phosphate buffer solution |
| Time of measurements | 2026 - 2027 |
| Status | Planned |
| References | |
| Measurand | pH from 6.80 to 7.00 |
| Parameters | Measurement temperature: 25 °C (optionally 15 °C and 37 °C) |
| Transfer device | Dedicated samples |
| Comparison type | Key Comparison |
| Consultative Committee | CCQM (Consultative Committee for Amount of Substance) |
| Conducted by | COOMET (Euro-Asian Cooperation of National Metrological Institutions) |
| RMO Internal Identifier | COOMET 630/RU/25 |
| Comments | The measurement method (primary method or secondary method using a differential potentiometric cell, or working method using a glass electrode pH-meter) is the choice of the each participant-laboratory based on its measurement capabilities. It is possible to use several methods, but only the results obtained by the primary method per temperature will be considered when calculating the key comparison reference value. |
| Pilot institute |
VNIIFTRI
Institute of Physical Technical and Radiotechnical Measurements, Rosstandart Russian Federation |
| Contact person | Narine Oganyan +79017227886 |
| Additional |
| Pilot laboratory | |
|---|---|
| VNIIFTRI |
Institute of Physical Technical and Radiotechnical Measurements, Rosstandart, Russian Federation, COOMET |
| RCAM-Rostest |
Research Center for Applied Metrology - Rostest, Russian Federation, COOMET |
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-K99
MEASURAND : pH value of an unknown phosphate buffer
Measurements at 15 °C, 25 °C, 37 °C. Optional: 5 °C and 50 °C.
NOMINAL VALUE : pH = 7.5
|
The key comparison reference value, pHR, is obtained by calculating the weighted mean including the institutes using primary standards for which the results passed a previously defined consistancy filter. t = 15 °C : pHR = 7.5561 and uR = 0.0009 t = 25 °C : pHR = 7.5246 and uR = 0.0008 t = 37 °C : pHR = 7.5013 and uR = 0.0009 t = 5 °C : pHR = 7.6043 and uR = 0.0015 t = 50 °C : pHR = 7.4960 and uR = 0.0029 |
| 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((1 - 2wi) ui2 + uR2)1/2, where wi represents the weight of laboratory i. |
CCQM-K99
MEASURAND : pH value of an unknown phosphate buffer
Measurements at 15 °C, 25 °C, 37 °C. Optional: 5 °C and 50 °C.
NOMINAL VALUE : pH = 7.5
pHi : result of measurement carried out by laboratory i
ui : combined standard uncertainty (k = 1) of pHi
