Metrohm 797 VA Computrace - Manual (Page 265)

8.10 Diagnostic procedures
797 VA Computrace – Software
253
c(Hg(II)) = 1 g/L to the empty measuring vessel at the 797 VA
Computrace stand.
3. Click on MAIN WINDOW / Utility / Film deposition to open the
FILM DEPOSITION window.
4. Enter suitable parameters in the parameter list.
5. Click on the
button.
6. Check the resulting test voltammogram. The voltammogram
should show low noise and a low background current (low μA
range). No interfering peaks should be visible.
Remove a mercury film
Mercury films can be easily wiped off manually with a tissue. The
cleaning procedure can be used instead to remove the mercury film
electrochemically or to clean the electrode surface after having re-
moved the mercury film mechanically.
1. Put the cleaning solution into the measuring vessel, e.g.:
Add 10 mL ultrapure water and 1 mL w(HNO
3
) = 0.65 to the
empty measuring vessel at the 797 VA Computrace stand.
2. Click on MAIN WINDOW / Utility / Cleaning procedure to open
the CLEANING PROCEDURE window.
3. Enter suitable parameters in the parameter list.
4. Click on the
button.
5. Check the resulting test voltammogram. The resulting voltam-
mogram should show low noise and a low background current
(low μA range). If all mercury had been oxidized, no mercury
peak remains.
8.10 Diagnostic procedures
Check the purging
1. Connect the inert gas to the 797 VA Computrace stand (see
Hardware Manual).
2. Make sure that the inert gas pressure is 1 ± 0.2 bar.
3. Add 20 mL ultrapure water to the empty measuring vessel at
the 797 VA Computrace stand.
4. Click on or MAIN WINDOW / Utility / Computrace control
to open the COMPUTRACE CONTROL window.
5. Select HMDE and click on .
6. Make sure that inert gas bubbles are purging through the solu-
tion.