4 sample subtraction, Sample subtr – YSI TruLab 1320P User Manual
Page 61
TruLab pH/ISE 1320
Ion concentration
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8.3.4 Sample subtraction
With the "Sample subtraction" procedure, a known amount of sample is added
to the standard solution (complexing agent or precipitating agent).
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 determination is possi-
ble.
Calibration
1.
Select the measuring method (see section 8.3 S
2.
If necessary, set the ion type for the ion in the standard (Ion type (sub))
with <> <> and <MENU/ENTER>.
On selection of the ion type that can be defined (ION):
Using <> <> and <MENU/ENTER>, set the valence (Valency) and
molar weight (Molar mass) for the ion in the standard solution.
3.
Select Continue with <> <> and confirm with <MENU/ENTER>.
i
Set the ion type for the standard.
Ion type
S
Continue
Sample subtraction
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4.
Prepare two standard calibration solutions.
5.
Perform a two-point calibration according to user guidance.
6.
The calibration record is displayed as soon as a stable value is
achieved for the second standard calibration solution.
CALIBRATION
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#1 0.010 mg/l
79.2 mV 25.0 °C
#2 0.100 mg/l
20.2 mV 25.0 °C
Slp.: -59.0 mV
Sensor +++ (Ion type: S)
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12:12
Continue
USB output