Maintenance; Cleaning The Instrument; Maintenance Of Electrodes - Mettler Toledo SevenExcellence Instrucciones De Instalación

6 Maintenance
6.1 Cleaning the Instrument
The instruments do not require any maintenance other than an occasional wipe with a damp cloth.
The housing is made of acrylonitrile butadiene styrene/polycarbonate (ABS/PC). This material is
sensitive to some organic solvents, such as toluene, xylene and methyl ethyl ketone (MEK).
Any spillage should be wiped off immediately.
6.2 Maintenance of Electrodes
The instrument monitors the condition of the attached pH electrodes.
Slope: 95-105%
and offset: ± (0-20) mV
Electrode is in good condition
When cleaning, always follow the instructions in the manual of the electrodes used. Make sure the
pH electrode is always kept filled with the appropriate filling solution. For maximum accuracy, any
filling solution that may have "crept" and encrusted the outside of the electrode should be removed
with deionized water. Always store the electrode according to the manufacturer's instructions and
do not allow it to dry out.
If the electrode slope falls rapidly, or if the response becomes sluggish, the following procedures
may help. Try one of the following, depending on your sample.
Problem
Fat or oil build-up
pH electrode membrane
has dried out
Protein build-up in the
diaphragm of a pH elec­
trode
Silver sulfide contamina­
tion of pH electrode
Run a new calibration after treatment.
Note
Cleaning and filling solutions should be handled with the same care as that given to toxic or corro­
sive substances.
The condition of the pH electrode can also be checked, using the provided METTLER TOLEDO
method Sensor Test.
20

Maintenance

Slope: 90-94%
or offset: ± (20-35) mV
Electrode needs cleaning
Action
Degrease the membrane with cotton wool soaked in either
acetone or a soap solution.
Soak the tip of the electrode overnight in 0.1M HCl.
If this procedure has no effect, soak the tip of the electrode
for a few minutes in reactivation solution for pH electrodes.
Remove deposits by soaking the electrode in an HCl/pepsin
solution.
Remove deposits by soaking electrode in a thiourea solution.
Slope: 85-89%
or offset: ± (>35) mV
Electrode is defective