Measuring / operation
NH 500/2
14
4.3
Response time
The response time depends very much on the concentration of the measured
ion, the condition of the electrode and the direction of the concentration
change.
For a 10-fold concentration change from 50 to 5 mg/l NH
4
-N, the response
time t
99
is < 8 min.
4.4
Interferences
l
Volatile bases, e.g. amines.
l
Coatings on the membrane (e.g. metal hydroxides)
4.5
Storage
4.6
Aging
The glass part of the electrode that is visible when exchanging the membrane
cap is a special pH electrode. Please note that it undergoes a natural aging
process. If the required slope cannot be achieved despite having changed
the membrane cap, the pH electrode is exhausted.
The pH electrode is unsuitable for conventional pH measurement. This case
as well as using unsuitable electrolytes and mechanical damage invalidates
any warranty claim.
Storage duration
Way of storing
Up to approx. two
days
Put in NH
3
electrolyte solution
with the membrane cap screwed on
For more than two
days
Store the electrode as follows:
l
Unscrew the membrane cap
l
Rinse the electrode
l
Fill some drops of tapwater in the storing cap
and screw it on. Thus the glass membrane will
remain conditioned.