Metrohm 817 Bioscan - Manual (Page 67)

5.2 Maintenance and servicing
817 Bioscan
59
5.2.3 Cleaning the working electrode
The surface of the gold working electrode should be cleaned whenever
you notice that its electrochemical properties have changed. This may
be caused by the deposition of reaction products. High current flows
can also alter the electrode surface; this is indicated by a very reduced
sensitivity after longer periods of use.
In principle, you should avoid too high analyte concentrations or dirty
samples. This measure as well as the regenerative effect of the pulse
technique normally supersedes the polishing of the electrode.
You should only polish the electrode surface with the polishing paste
supplied when the sensitivity cannot be restored by intensive rinsing
of the flowcell with water and cleaning the electrode surface with a
tissue soaked in ethanol or acetone.
Use the diamond paste (6.2802.110) supplied to polish the surface of
the electrode together with the polishing disk (6.2802.100). Proceed as
follows:
1 Rinse the polishing disk
Rinse the polishing disk with water (distilled or deionized) before
use.
2 Shake the diamond paste
Shake the bottle containing the diamond paste thoroughly
before use.
3 Polish the electrode
Add a few drops of the paste to the wet paste to the wet polish-
ing disk and polish the electrode for approx. one minute with
uniform movements in the form of a figure 8. Exert only a slight
pressure.
4 Clean the electrode
Clean the electrode with a paper tissue moistened with ethanol.
Check the surface condition visually and repeat the polishing
process if necessary.
5 Mount the flow-through cell
Remount the detector cell as described in Section 2.3.5. Pay
attention to an exact fitting of the spacer, the right position of
both markers
35, and a correct screw joint (s. section 2.3.5).
6 Clean the polishing disk
Clean the polishing disk with water (distilled/deionized) and
store it dust-free in its plastic cover.