Calibration; Why Calibrate; When To Calibrate; Calibration (Ise Cal) - wtw pH/ION 7320P Operating Manual

Ion concentration
48
8.2

Calibration

8.2.1 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 calibration line of the electrode and stores this value in the
meter.
Thus, you should calibrate before each measurement and at regular intervals.

8.2.2 When to calibrate?

 Before any measurement if possible
 After connecting another ISE electrode
 When the sensor symbol flashes, e.g. after a voltage interruption (empty
batteries)

8.2.3 Calibration (ISE Cal)

ISE Cal is the conventional two-point to seven-point calibration procedure
that uses 2 to 7 freely selectable standard solutions. The concentration
expected for the measurement determines the concentration of the calibration
standards.
1. Connect the ISE combination electrode to the meter.
The pH/mV/ISE measuring window is displayed.
2. Keep the standard solutions ready.
3. If necessary, measure the temperature of the standard solutions with a
thermometer.
4. If necessary, change the unit of the measurement result and calibration
standards in the ISE setup/Unit menu.
5. In the measured value display, select the ISE measuring window with
<> <> and <M>.
6. Start the calibration with <CAL>.
The calibration display appears.
ISE
24.8 °C
Ag
1
Standard
0.0
mV
0.010
mg/l
12.12.2012
12:12
pH/ION 7320
ba75935e04 12/2017