Metrohm viva 1.0 Manual - Manual (Page 872)

9.2 Troubleshooting
￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭
860 ￭￭￭￭￭￭￭￭
viva 1.0
Problem Cause Remedy
The working electrode is
contaminated. Condition the working electrode in pure VMS.
The electrode tip of the
working electrode has
been in use for a long
period. ￭ Immerse the electrode tip in c(NaOH) =
0.5 mol/L for approx. 10 min and then
thoroughly rinse with distilled water.
￭ Replace electrode tip if necessary.
VMS is contaminated. Check reagents for purity. (Only reagents of
sufficient purity, i.e. > 99%, should be used.)
The water quality is poor. Use distilled water, type-II grade (ASTM
D1193-91) or higher.
The measuring solution has
been contaminated as a
result of diffusion. No infeed tubing other than the 4-fold micro
dosing tip (6.1824.000) may be immersed in
the measuring solution.
Solution is leaking
between the mea-
suring instrument
and the measuring
head. The measuring head is not
correctly locked in place on
the measuring head arm. Let the measuring head snap into place. The
click must be audible.
The sealing rings have
aged or are defective. Contact the Metrohm Service department.
The electrode test
fails. One or several electrodes
are not connected. Check the electrode cable connections.
One or several electrodes
are defective. Perform maintenance in accordance with the
electrode leaflet.
The measuring vessel con-
tains too little solution or is
empty. Check the fill level in the measuring vessel and
add solution if necessary.
The electrode tip of
the working elec-
trode and/or the
auxiliary electrode
shows copper
deposits. An incorrect potential has
been applied because the
reference electrode is
defective. ￭ Check the reference electrode; perform
maintenance procedure in accordance with
the electrode leaflet, if necessary.
￭ Dip the electrode tip of the working elec-
trode and/or the auxiliary electrode into
concentrated nitric acid for 1 to 2 seconds
and then thoroughly rinse with distilled
water.
An incorrect potential was
applied because the refer-
ence electrode is not con-
nected. ￭ Check the electrode connectors.