Metrohm 907 Titrando - Manual (Page 51)

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6 Troubleshooting
907 Titrando
￭￭￭￭￭￭￭￭ 43
Problem Cause Remedy
￭ 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. ￭ Select the user-defined titration rate and
reduce the dosing rate (see manual/help of
the software used).
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.
The electrode has a short
circuit. 1. Check the Pt wires.
2. Activate the electrode check.
The endpoint is
reached too quickly. The dosing rate outside the
control range is too high. Select the user-defined titration rate and
reduce the dosing rate (see manual/help of the
software used).
The titration times
with volumetric
titration are con-
stantly longer. The buffer capacity of the
solvent may be exhausted
with two-component
reagents. Replace the working medium.