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3.4 Specific Ion Calibration Notes
1.
A Primary Calibration should be performed at least weekly. In applications where the reference
electrode junction can become blocked, such as dairy products, mining slurries etc, a Primary
Calibration may have to be done daily.
2.
A full Primary and Secondary Calibration should be performed at least monthly. Of course,
more frequent calibration will result in greater confidence in results.
3.
Calibration information for each Channel is retained in memory when the
900-I3
is switched
off, even when the power supply is removed. This information can be recalled or printed later
using the GLP function (see section 8).
4.
The
900-I3
displays the value of the standard to which it will attempt to calibrate. Ensure that
the standard value displayed corresponds to the standard that you are using. Alter the Standards
set-up if necessary (see section 3.2).
3.5 Specific Ion Calibration Messages
1.
If a Primary Calibration has been successfully performed, the
900-I3
will display the following
message, and the Offset value of the sensor. For example…
100
100
∗∗
ppM 25.0
ppM 25.0
O
O
c
c
Calibration OK. mV @ STD1=0.1mV
Calibration OK. mV @ STD1=0.1mV
2.
If a Secondary Calibration has been successfully performed, the
900-I3
will display the
following message, and the slope value of the sensor. For example…
10.0ppM 56.7mV 25.0
10.0ppM 56.7mV 25.0
O
O
c
c
Calibration OK. Slope=95.6%
Calibration OK. Slope=95.6%
3.
If a Secondary Calibration has failed, the
900-I3
will display the following message, and the
failed slope value of the electrode. For example…
35
35
∗∗
2ppM 25.4mV 25.0
2ppM 25.4mV 25.0
O
O
c
c
Calibration Failed. Slope=42%
Calibration Failed. Slope=42%
Notes
1.
The
900-I3
has an unlimited Offset range, as long as the reading is not over-ranged.
This is to allow for the large variety of Ion Selective Electrodes available.
2.
The allowable Slope range is 50.0 to 110.0 %. This range is ample to allow for correctly
functioning Ion Selective Electrodes. If calibration fails due to the Slope being outside these
limits, then please consult the Troubleshooting guide (section 16.2) for possible remedies.