Xylem ProLab 4000 MULTIPARAMETER BENCHTOP METER - Manual (Page 119)

ProLab 4000 Ion concentration
119 ba75646e02 01/2010
9.6.4 Standard subtraction
In the "Standard Subtraction" procedure, a known amount of standard
solution is added to the sample (as complexing agent or precipitating
agent) and, thus, the ion concentration lowered.
The ion concentration in the sample is calculated from the change in
potential.
Calibration
Measuring
1 Check the currently displayed ion.
If the ion to be measured is displayed incorrectly:
Select the ion type in the menu, Measuring / ISE methods / Ion
type.
2 In the Measuring / ISE methods menu, select the method,
Standard subtraction.
3 Carry out a two-point calibration according to the user guid-
ance (see page 106).
As soon as a stable value is achieved for the second standard
calibration solution, the slope (mV) and evaluation (Error, +++)
of the electrode after calibration is displayed.
The infotext, Accept calibration and terminate is displayed.
4 Using [OK], confirm the infotext Accept calibration and termi-
nate.
The calibration record is displayed and output to the interface.
The calibration procedure is finished.
5 Close the calibration record with [OK].
The ISE method: The Standard subtraction window pops up.
The Sample register is displayed.