Relative Millivolts
mV Measurement
Select the mV mode by using the arrow keys and pressing . The instrument can toggle between Absolute
and Relative millivolts by using the key with REL or ABS menu option highlighted. Relative mV is
indicated by REL appearing on the display.
3.13 TEMPERATURE MEASUREMENT
The instrument will operate with one or two probes connected for automatic temperature compensation. If
two probes are connected and one fails, the instrument will automatically revert to the remaining good sensor
and both displays will show this value.
If both sensors fail the instrument will revert to manual temperature measurement.
Manual values can be entered via the SETUP and INSTRUMENT SETUP... menus and selecting MAN
TEMPERATURE using the arrow keys and pressing . Adjustment is made using the numeric keypad
and pressing .
This mode is suitable for determinations using Redox and Ion Selective Electrodes and has the additional
benefit of being able to zero any offset voltage developed by the electrode in a blank solution, i.e; a solution
that has none of the ions to be measured, but has all the other characteristics of the unknown samples. A
blank solution would normally have its ionic strength and pH adjusted as required for the electrode in use.
As the display is zeroed automatically when the Relative millivolt mode is selected, it is necessary to immerse
the electrode in the blank solution with the Absolute mV mode selected. When the reading has stabilised the
Relative mV mode should then be selected. The display will be set to zero, thereby removing any offset
voltage.
Sample measurement is then carried out by using a variety of well tried analytical methods; from simple
calibration curves through titrations, to single and multiple addition methods.
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