Metrohm 917 - Page 307

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30 Troubleshooting
917 Coulometer
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293
Problem Cause Remedy
The sample contains oxi-
dizable substances.
￭ Consider using a KF oven.
￭ See technical literature.
The parameter Stop drift
is set too low.
￭ Set the Stop drift higher or use the Rela-
tive stop drift.
The drift correction is too
small (e.g. for the use of a
KF oven or for manual drift
correction).
￭ Start the titration as long as the gas flow
still exists between the conditioning vial
and the titration cell.
￭ Set the parameter Drift correction to
auto (= automatic drift correction).
The result is too
low.
The sample releases iodine. ￭ Consider using a KF oven.
￭ See technical literature.
The parameter Stop drift
is set too high.
￭ Set the Stop drift lower.
The drift correction is too
large (e.g. with excessively
high start drift, with fluctu-
ating drift or with manual
drift correction).
￭ Ensure stable and lower drift.
￭ Set the parameter Drift correction to
auto (= automatic drift correction).
The parameter Min. rate
is set too low.
￭ Set the parameter Min. rate higher.
￭ Reset the Control parameters to default
values.
The results are
spread widely.
The sample is nonhomoge-
nous.
￭ Homogenize the sample if possible.
￭ Possibly use a larger sample size.
The sample addition is diffi-
cult to reproduce.
￭ Observe the instructions in .
The drift fluctuates. ￭ Ensure stable drift.