SCHOTT Instruments ProLab 2000 - Calibrating for ISE Measurements

ProLab 2000 Operation
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ba75577e03 11/2009
4.6.4 Calibrating for ISE measurements
Why calibrate? Ion-selective electrodes age and are temperature-dependent. This
changes the slope. As a result, an inexact measured value is displayed.
Calibration determines the current value of the slope of the electrode
and stores it in the instrument.
Thus, you should calibrate before each measurement and at regular
intervals.
When to calibrate? z Before any measurement if possible
z After connecting another ISE electrode
z When the CalClock flashes, e. g. after a voltage interruption
Standard solutions Use two or three different standard solutions. For three-point
calibration, the standard solutions have to be selected in either
increasing or decreasing order.
Note
The measurement precision is also dependent on the selected
standard solutions. Therefore, the selected standard solutions should
cover the expected value range of the subsequent concentration
measurement.
Menu item Possible
setting
Description
Calibration /
Calibration record
- Displays the calibration
record of the last calibration.
Man. temperature -20 ... +130 °C Entry of the manually
determined temperature. For
measurements without
temperature sensor only.
Standard
solution
Values [mg/l]
Std 1 0.01; 0.02; 0.05; 0.1; 0.2; 0.5; 1; 2; 5; 10; 20; 50; 100;
200; 500; 1000
If Std 2
> Std 1, Std 3 must be > Std 2
If Std 2
< Std 1, Std 3 must be < Std 2
Std 2
Std 3