Metrohm 899 Coulometer - Manual (Page 99)

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9 Troubleshooting
899 Coulometer
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9 Troubleshooting
9.1 Karl Fischer titration
Problem Cause Remedy
The drift is very high
during conditioning. The coulometer cell is not
leak-proof. ￭ Check the septum and replace it if neces-
sary.
￭ Replace the molecular sieve.
￭ Check the ground-joint sleeves for frayed
edges. If necessary, trim the edges cleanly
or replace the ground-joint sleeves.
Aqueous deposits are to be
found in the coulometer
cell. ￭ Shake the coulometer cell.
The reagent is exhausted
or contaminated. ￭ Replace the reagent.
The catholyte is old or
moist. ￭ The catholyte must be replaced at least
once per week.
￭ Dry the catholyte with KF single-compo-
nent reagent.
The diaphragm of the gen-
erator electrode is conta-
minated. ￭ Clean the diaphragm (in accordance with
directions in the leaflet for the generator
electrode).
A side reaction is taking
place. ￭ Possibly use a KF oven.
￭ See technical literature.
The molecular sieve on the
KF oven has reached its
capacity limit. ￭ Replace the molecular sieve.
The gas flow from the KF
oven into the coulometer
cell is too high. ￭ Reduce the gas flow (if you are working
with the oven method with sample vials,
set the gas flow between 40…60 mL/min).
The drift becomes
greater after each
titration. The sample releases water
very slowly. ￭ Possibly use a KF oven.
￭ See technical literature.
The drift is fluctuat-
ing. The sample solution is
poorly stirred. ￭ Set the stirring rate in such a way that the
sample solution will become very well
mixed.