eutech-instruments bromide epoxy Manuale Utente
Instruction Manual
Bromide Electrode
12
If the temperature varies substantially from room temperature, equilibrium times up to one hour are
recommended.
recommended.
Electrode Response
Plotting the electrode mV potential against the bromide concentration on semi-logarithmic paper
results in a straight line with a slope of about 57 mV per decade. (Refer to Figure 1.)
The time needed to reach 99% of the stable electrode potential reading, the electrode response time,
varies from several seconds in highly concentrated solutions to several minutes near the detection
limit. (Refer to Figure 2.)
A drifting potential reading or a decrease in electrode slope may mean that the electrode membrane
needs polishing.
To polish the membrane:
1.
If using polishing paper, cut off a 1-2" piece and place it face up on the lab bench.
2.
Put a few drops of distilled or deionized water in the center of the paper.
3.
Holding the paper (cotton) steady with one hand, bring the membrane of the electrode
down perpendicular to the paper and, with a slight swirling motion, gently polish the tip of
the electrode against the surface of the polishing paper (cotton) for a few seconds.
down perpendicular to the paper and, with a slight swirling motion, gently polish the tip of
the electrode against the surface of the polishing paper (cotton) for a few seconds.
4.
Rinse the electrode surface with distilled or deionized water and soak the electrode tip in
standard solution for about five minutes before use.
standard solution for about five minutes before use.
5.
If using jeweller's rouge, place a cotton ball on the table top and flatten it using the bottom
of a beaker. Put 1-2 drops of distilled or deionized water in the center of the cotton pad.
Add a small amount of jeweller's rouge to the damp cotton.
of a beaker. Put 1-2 drops of distilled or deionized water in the center of the cotton pad.
Add a small amount of jeweller's rouge to the damp cotton.
6.
Continue with Steps 3 and 4 above.