Xylem ProLab 4000 MULTIPARAMETER BENCHTOP METER - Manual (Page 128)

Ion concentration ProLab 4000
128 ba75646e02 01/2010
9.6.7 Blank value addition (Standard addition with
blank value correction)
In the "Standard addition with blank value correction" procedure, a
known amount of standard solution is added to the sample in two steps.
With the first addition, the ion concentration is raised to the linear range
of the electrode characteristic curve.
The second addition is equivalent to the standard addition.
The ion concentration in the sample is calculated from the change in
potential.
Calibration
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,
Blank value addition.
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 Blank value addition window pops up.
The Sample register is displayed.