Version:
Page:
Issue Date:
02
1 of 1
3 June 1990
pH REFERENCE ELECTRODE JUNCTION POTENTIAL CHECK
pH Electrode Description or Serial No.:
DATE
pH 6.88
BUFFER
1:10 pH 6.88
BUFFER
TEMP C
ANALYST
CHECK
Measure of Reference Electrode Junction Potential
The effect of junction potential can be checked by measuring the pH, of preferably a pH 6.88
phosphate buffer solution and comparing it with the pH of the same buffer solution diluted with 9
parts of freshly boiled distilled water. Pipette 5ml pH 6.88 buffer and dilute to 50mL in a
volumetric flask with freshly distilled water. The pH of the diluted buffer should be 0.20.05units
higher than the original buffer. If the value obtained is outside the range, the reference electrode
may require attention. Inform the Shift Chemist.
pH range = 7.03 –7.13
To make pH 6.88 buffer, add 3.387g KH2PO4 and 3.533g Na2HPO4 to 1L volumetric flask and make
to volume with freshly boiled (carbon dioxide free) distilled water and mix well.
05-022