Appendix 1
-
pH electrodes
Before Use
Remove the protective cap covering the glass sensing bulb and replace with the
protective guard if applicable. Inspect the filling solution for air bubbles and remove
by shaking in a downward direction. Soak the electrode in pH storage solution for 30
minutes.
Cleaning
Soak the electrode in 0.1M HCl for 15 minutes followed by soaking in pH storage
solution for 30 minutes
Storage.
Put some pH storage solution in the protective cap and place over the glass bulb.
Never store the electrode in distilled or de-ionised water. Never allow the electrode to
dry out.
pH electrode storage solution is made up by dissolving 1g KCl in 100mL of pH 7 buffer
pH Buffers
- Buffer Capsules
Buffer capsules are made up as follows For each buffer, empty the powder into a
suitable container. Using deionised water, make up to 100mL ensuring that the
powder is filly dissolved before use. The coloured outer skin may be added to colour
code the resulting buffer. This may take up to 4 hours to dissolve but will not affect
the pH of the buffer.
Buffer Solutions
If using ready made solutions, use ones supplied with temperature coefficient
information.
Table of Temperature Coefficients For EDT Buffers
°C pH
4 pH
7 pH
pH10
10
3.99
7.07
10.18
15
4.00
7.04
10.14
20
4.00
7.02
10.06
25
4.00
7.00
10.00
30
4.00
6.99
9.95
35
4.01
6.98
9.91
40
4.02
6.97
9.85
50
4.05
6.96
9.78
60
4.07
6.96
9.75
