EVOM
3.
Lightly
rub the voltage electrode
(silver pellet on the inner surface near
the electrode tips) of the
STX2
with the
600-grade Ultra Fine sandpaper provided
(see Fig. 2). Only a very thin surface layer
of the pellet should be removed. Repeated
rubbing will eventually remove the Ag/AgCl
pellets. When rubbing no longer improves
the voltage readings, the electrode should
be replaced. In the absence of 600-grade
sandpaper, an ink eraser may be substituted
to clean the electrodes.
Sterilizing the STX2 Electrode
The
STX2
electrodes are non-sterile as
supplied. They may be sterilized using
alcohol (one of the most common methods), ethylene oxide, UV, or a bactericide,
e.g.,
Cidex Plus (WPI #
7364
) or Sporicidin.
NOTE:
The electrode cannot be sterilized by autoclaving
A Typical Sterilization Protocol Using Alcohol
Do not leave the electrode in alcohol for more than 30 minutes each time. Continuously
soaking the electrode in alcohol will weaken the protective coating on the electrode and
shorten its lifetime.
In a laminar flow hood:
1.
Immerse the electrodes in 70% ethanol for 15 minutes. Allow them to air dry for 15
seconds.
2.
Rinse the electrode in a sterile electrolyte solution similar to the experimental cell
culture medium or in 0.1 – 0.15 M KCl or NaCl.
3.
For
resistance
measurements, the electrode is now ready to use.
4.
For
voltage
measurements, allow the electrode to equilibrate in the sterile electrolyte
for 15 minutes. Then, adjust the “voltage zero” on the
EVOM
to balance any residual
offset between the two probes.
The electrode can be left in a UV hood to keep it sterile.
NOTE:
When the electrode is exposed to strong visible or UV light, a dark colored oxide
film will slowly form on the electrode surface. This film normally will not affect the
WORLD PRECISION INSTRUMENTS 11
STX2
sand lightly
NO
sanding!
NO
sanding!
Fig. 2
