Metrohm tiamo 2.3 (process analysis) - Manual (Page 580)

5.6 Commands ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭
564 ￭￭￭￭￭￭￭￭ tiamo 2.3 (for Process Analysis)
Principle
With this command titrations with reagent addition at constant volume
increments are carried out. Measured value acceptance is drift-controlled
(equilibrium titration) or after a waiting time.
Note
This command is suited for titrations with relatively high signal fluctua-
tions or suddenly occurring potential jumps and for slow titrations or
slowly responding electrodes.
Evaluation
The equivalence points (EPs) are automatically localized by a method
based on the Fortuin method which has been adapted by Metrohm for
numerical methods. A search is made for the largest measured value mod-
ification (∆
n
). The exact EP is determined by using an interpolation factor
ρ which depends on the ∆ values before and after ∆
n
.
V
EP
= V
0
+ ρ ∆V
V
EP
= EP volume, V
0
= total volume dosed before ∆
n
, ∆V = volume incre-
ment, ρ = interpolation factor according to Fortuin
For the recognition of the EPs found, the set EP criterion is compared
with the ERC (Equivalence point Recognition Criterion) found. The ERC is
the sum of the measured value modifications before and after the jump:
|∆
n-2
|+|∆
n-1
|+|∆
n
|+|∆
n+1
|+|∆
n+2
|
(In certain cases, only three or only one summand is taken into account.)
EPs whose ERC is smaller than the set EP criterion will not be recognized.