Metrohm 827 pH lab - Manual (Page 51)

8 Troubleshooting – Messages – Maintenance
826/827 pH meter, Instructions for Use
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8 Troubleshooting – Messages –
Maintenance
8.1 Troubleshooting
If problems occur during pH measurement then these can have various
causes:
1. Application
Difficult sample matrices or interferences can prevent reliable mea-
surements (e. g. insufficient ionic strength). Our Application Bulle-
tins and Application Notes support you in correct selection of the
analytical conditions. The most suitable electrode for your applica-
tion can be found under www.metrohm.com.
2. Buffer solution
The precision of pH measurements depends primarily on the correct
calibration of the electrode. You should use clean and fresh buffer
solutions. For example, a frequent cause of incorrect calibration is
the use of an old pH 9 or pH 10 buffer, whose pH can vary consi-
derably from the certified pH of a new buffer as a result of the ab-
sorption of atmospheric CO
2
.
3. Measuring / Reference electrode
The electrodes are the most important element of the whole measur-
ing system. The correct handling of the measuring and reference
electrodes is described in the leaflet which accompanies the elec-
trode.
4. pH meter
If the pH meter is thought to be the cause of a measuring problem
then first check all the configuration and parameter settings. The di-
agnostic functions help you in searching for the fault (see Sec-
tion 8.3).
The pH meter will inform you directly about problems during the mea-
surement. These messages are explained in the following Section 8.2.
The following table lists general problems that can occur during pH
measurements. Possible causes and appropriate remedies are also
described.