horiba 5002S-10C, Instruction Manual

Page: 71 / 79

59
Reference
The optimal way to minimize the impact of temperature on the
measurement of the ammonium ion concentration is to reduce the
difference between the temperature of the standard solution in calibration
and the temperature of the sample solution in measurement to ±1°C.
The following table shows the change in the theoretical slope of the
ammonia electrode depending on the temperature of the ammonia
electrode.
Table 4 Relationship between temperature of
ammonia electrode and theoretical slope
If the temperature of the sample solution in measurement differs from the
temperature of the standard solution in calibration, perform calibration
again.
When the electrode is moved to a place that has a different temperature,
wait until the temperature of the electrode becomes same as the
temperature of that place before using the electrode.

Impact of stirring
The impacts on the measurement of the electromotive force by stirring the
sample solution inappropriately are, for example, slow response, inability to
measure the low concentration solution, and the change of the electrode
potential.
It is best to control the stirring speed so that the stir bar will rotate 3 or 4
turns per second.
If swirling occurs on the surface, the stirring speed is too fast. Reduce the
speed to a level where swirling does not occur.
Temperature
[°C]
Theoretical slope of ammonia electrode
[mV/decade] (mV/concentration change of 10 times)
0 54.20
10 56.18
20 58.16
25 59.16
30 60.15
40 62.13
50 64.11