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 a phosphate buffer |
| Time of measurements | 2025 |
| Status | Planned |
| Measurand | Acidity function at zero chloride molality of an phosphate buffer |
| Parameters | pH ~ 7.5 Measurement temperatures: 15 °C, 25 °C, 37 °C |
| Comparison type | Key Comparison |
| Consultative Committee | CCQM (Consultative Committee for Amount of Substance) |
| Conducted by | CCQM (Consultative Committee for Amount of Substance) |
| Comments | This key comparison is a bilateral, subsequent key comparison to CCQM-K99 on the pH of an unknown phosphate buffer. PTB will be the linking laboratory. pH is one of the fundamental properties of aqueous solutions and is measured routinely in laboratories. This study aims to evaluate the degree of equivalence of the primary pH measurements at KRISS with the key comparison value of CCQM-K99, and aims to support respective CMCs in the KCDB. |
| Pilot institute |
KRISS
Korea Research Institute of Standards and Science Korea, Republic of |
| Contact person | Min-Ah Oh +820428685779 |
| Additional |
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
