Titra
Lab
®
TitraLab 870 Reference Manual
Page 271
6. ISE measurements - ISE standard addition method
In an ISE standard addition method, the additions are automatically performed using a pre-
programmed standard addition reagent. The addition volumes can be programmed or
automatically determined.
In the case of programmed volumes, the user selects the standard reagent, enters the
volume of one addition then the number of additions to be performed.
In the case of automatically determined volumes, the TIM870 calculates the volume to add in
order to get a potential jump (
∆
E total) due to all additions (n additions) equal to a user-
selectable value (between 5 and 100 mV). The potential jump per addition (dE) is then
determined by:
The dE minimum value is 2 mV. The algorithm starts with addition of small volumes in order to
determine the volume to be added to reach the potential jump target.
Calculation principle (for programmed or automatically determined additions):
The Cs sample concentration is determined using an iterative calculation on this following
equation:
•
C
S
= sample concentration
•
V = sample initial volume
•
C
a
= concentration of the addition
•
V
i
= volume of the addition
•
V
elec
= volume of electrolyte added
•
T = temperature (mean of all measured points).
GRAN representation:
We use the GRAN = f(V) graphical representation allows to show the dispersion of the
experimental points regarding the regression straight line.
The GRAN=f(V) curve is displayed in the "More details" menu. This curve can be printed at
the end of analysis if asked for in the Edit method > Printouts menu.
During an ISE standard addition measurement, the temperature cannot vary by more than
5°C
. A warning message (dT>5) is displayed and the result is rejected if this condition is not
fulfilled.
mV
n
E
dE
total
2
≥
∆
=
(
)
»
¼
º
«
¬
ª
+
+
+
×
×
−
=
i
elec
i
a
S
i
V
V
V
V
C
V
C
T
T
S
E
E
log
25
25
0
(
)
)
(
10
25
25
0
)
(
Vi
GRAN
V
V
V
V
V
elec
i
elec
T
S
T
E
E
i
=
+
+
+
×
−
Summary of Contents for TitraLab 870
Page 1: ...TitraLab 870 pH EP IP EC ISE Titration Workstation Reference Manual D21T060...
Page 2: ...D21T060 Printed by Radiometer Analytical SAS 2008 02F...
Page 22: ...TitraLab TitraLab 870 Reference Manual Page 22...
Page 23: ...Practical examples s...
Page 24: ......
Page 32: ...TitraLab TitraLab 870 Reference Manual Page 32...
Page 40: ...TitraLab TitraLab 870 Reference Manual Page 40...
Page 41: ...Glossary...
Page 42: ......
Page 255: ...Appendixes...
Page 256: ......
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Page 262: ...TitraLab TitraLab 870 Reference Manual Page 262...
Page 280: ...TitraLab TitraLab 870 Reference Manual Page 280...
Page 286: ...TitraLab TitraLab 870 Reference Manual Page 286...
