Metrohm 915 KF Ti-Touch - Manual (Page 350)

30.7 Karl Fischer titration
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915 KF Ti-Touch
Problem Cause Remedy
A side reaction is taking
place. ￭ Use special reagents.
￭ Adjust the method (increase/decrease the
temperature, external extraction).
￭ See technical literature.
The pH value is not in the
optimum range anymore. Add buffer, see technical literature.
The titration will not
be finished. The titration cell is leaking. ￭ Check seals and septum. If necessary,
replace.
￭ Replace the molecular sieve.
The minimum increment is
too low. Define Titration rate = user and increase the
minimum volume increment (Min. incre-
ment) (see Chapter 28.1.2, page 261).
The stop criterion is unsuit-
able. Adjust the control parameters (see Chapter
28.1.2, page 261):
￭ Increase the stop drift.
￭ Select a short delay time.
See also: The drift becomes
greater after each titration.
The sample is over-
titrated. The increments at the end
of the titration are too
high. ￭ Define Titration rate = user and reduce
the dosing rate (Max. rate) (see Chapter
28.1.2, page 261).
The following experiment provides a clue
for the optimum dosing rate: During condi-
tioning, display the drift and add sample
without starting the titration. Select a value
below the highest drift as dosing rate.
￭ Stir faster.
The amount of methanol in
the working medium is too
low. ￭ Replace the working medium.
￭ Reduce the amount of solubility promoter,
if working with solvent mixtures, see tech-
nical literature.
The electrode may be cov-
ered. Wipe off the electrode with ethanol or a suit-
able solvent.
The solution
becomes darker
after each titration. Replace the working medium.
The electrode may be cov-
ered. Wipe off the electrode with ethanol or a suit-
able solvent.