inoLab pH/ION 735
Operation
53
4.5.9
Sample subtraction (
Sample sub.
)
In the "Sample Subtraction" procedure, a known amount of sample is
added to the standard solution.
The ion concentration in the sample is calculated from the change in
potential.
The sample subtraction is one method for the indirect determination of
ions. It is used for the determination of ions for which no direct determi-
nation is possible.
Measuring
1
Select the measuring method (see section 4.5.5).
2
Prepare two standard calibration solutions.
3
Perform a two-point calibration according to the user guidance.
4
As soon as a stable value is achieved for the second standard
calibration solution, the slope (mV) and evaluation (+ ... +++) of
the electrode after calibration is displayed.
i
Slope =
33.6 mV
i
Sensor
+++
Accept
ISE <CAL>
5
Start the measurement with
g
An entry window appears.
6
Thoroughly rinse the electrode with deionized water.
7
Immerse the electrode in the standard solution.
8
Using
82
and
g
, enter the values for the volume of the
standard solution (
Std. volume
), the concentration of the stan-
dard solution (
Std. concentration
) and the volume of the ISA/TI-
SAB solution (
ISA/TISAB vol.
).
i
Immerse sensor in std.
Std. volume
100.0 ml
Std. concentration
1.0 mg/l
ISA/TISAB vol.
1.0 ml
Continue
Sample subtraction
