3.12 mV MODE - SETTING UP PARAMETERS
EXIT
menu escape key
RESOLUTION
allows the number of decimal places for the measured parameter on the dis
play to be changed using the arrow keys
ALARM POINTS....
allows the alarm points for the selected mode and channel to be viewed and
changed
INSTRUMENT SETUP...
used to select the next set up menu for instrument parameters
RESOLUTION
Enter mV SETUP menu and select RESOLUTION. Select the preferred resolution (0.1 or 1mV) from pre-
defined options using the arrow keys and press .
Absolute Millivolts
When this mode is selected the unit will display the actual voltage developed by the electrode when it is
immersed in a solution containing ions to which the electrode is sensitive.
The electrode may be a combination type or a suitable sensing/reference pair, depending on the specific test
being carried out.
pH, Redox and Ion Selective electrodes can all be used in this mode. Most of these determinations will
require the preparation of calibration curves or other analytical methods to enable the mV reading to be
converted to a concentration unit. For further information on these determinations refer to the electrode
instructions, which will normally give details of calibration solutions, interferences and the limits of the
methodology.
A very useful application of the Absolute mV range is for monitoring the performance of standard pH
electrodes. Using accurate and fresh buffers at a constant temperature, the millivolt output of the electrode
should be noted and compared to the theoretical ideal. As the electrode ages, becomes contaminated or dirty,
these values will drift, indicating that corrective action should be taken.
Recording these values as part of a routine Quality Control program can give a good indication of the
condition of the electrode.
3345/REV A/08-99
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