Metrohm tiamo 2.2 (ProcessLab) - Manual (Page 561)

￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 5 Method
tiamo 2.2 (ProcessLab) ￭￭￭￭￭￭￭￭ 545
Note
This command is suited for titrations with relatively high signal fluctuations
or suddenly occurring potential jumps and for slow titrations or slowly
responding electrodes.
Evaluation
The equivalence points (EPs) are localized by a procedure based on the For-
tuin method which has been adapted by Metrohm for numerical methods.
A search is made for the largest measured value modification (∆
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 added 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.
Commands
Depending on the measured value one of the following four MET com-
mands can be selected:
￭ MET pH
Potentiometric pH measurement with pH electrodes (measured quantity
pH).