wtw inoLab 740, Operating Manual

Page: 119 / 274

Ion concentration
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7.4.3 Double Standard Addition ( Std Add ++ )
In the "Double Standard Addition" procedure, a known
amount of standard solution is added to the sample in two
steps.
The ion concentration in the sample is calculated from the
change in potential between the first and second addition of
standard solution.
To ensure reproducibility, the second addition of standard
solution must use a volume that is twice as big as the
volume used in the first addition.
Measuring
1 Start the measurement with [Start] .
A window for the entry of data opens.
2 Enter Sample volume and ISA/TISAB volume with
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and [Next] .
3 Thoroughly rinse the electrode with deionized water.
4 Immerse the electrode in the sample.
5 Start the measurement with [Start] .