Calibration – Hach-Lange HQD - Sodium (Na+) Ion Selective Electrode ISENa User Manual
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Calibration
Calibration notes
•
Probes are initially calibrated at the factory. However, regular calibration by the user is
recommended for the best measurement accuracy.
•
Open the filling-hole cap to allow proper flow of filling solution when in use.
•
Additional standard sets along with the minimum number of calibration points can be
selected in the ISENa381 Calibration Options.
•
The calibration is recorded in the electrode and the data log. The calibration is also
sent to a PC, printer or flash memory stick if connected.
•
Make sure the filling solution is above the sample level (
•
Select Skip to omit a standard from the calibration routine. The minimum number of
standards must be met for the Skip option to be displayed.
•
The user must begin with the lowest concentration during calibration. This reduces
carry over contamination to give optimal results.
•
For measurements below 1 ppm (10
-5
M), plastic lab-ware should be used.
•
All samples should be stirred consistently as the electrode potentials are dependent
on such stirring conditions.
•
Always rinse the electrode with an ISA rinse solution between measurements and blot
dry. Never use only deionized water. Refer to
ISA rinse solution preparation on
Before calibration
Note the temperatures of the standards during calibration. Temperatures between calibration standards should be kept within
± 1 ºC for optimal results.
The electrode must have the correct service-life time stamp. Set the date and time in the meter before attaching the
electrode.
It is not necessary to recalibrate when moving a calibrated electrode from one HQd meter to another if the additional meter is
configured to use the same calibration options. If the additional HQd meter uses different calibration options (e.g. standard
calibration routine), calibrate the electrode or change the method settings/select a different method.
To view current calibration, select DATA LOG key, View Probe Data, then View Current Calibration.
If any two probes are connected, push the
UP
or
DOWN
arrow to change to the single display mode and show the Calibrate
option.
Use an electromagnetic stirrer and stir samples at a moderate rate. Avoid resting the electrode on the bottom or sides of the
container.
If a calibration error occurs, recalibrate using fresh, high quality standard solutions. Refer to
The filling-hole must be open for the proper flow of the filling solution.
If custom calibration or measurements settings are desired, a new method can be created by accessing the ISENa381
Settings menu.