Metrohm 840 PC Control 5.0 / Touch Control - Manual (Page 215)

4 Parameters
PC Control / Touch Control
203
V
E
Inflection
point
pH
V/mL
Fig. 4.7: Tubbs method for determining the equivalence point
The figures shows that the evaluation also requires measuring points
after the equivalence point too.
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 first derivative of the titration curve combined with a mathematical
function which is more sensitive for flat jumps than for steeper ones.
EPs whose ERC is smaller than the set EP criterion will not be recog-
nized. The ERC for each found and recognized EP will be shown under
Results/Curve/EP Details . If you subsequently adapt the EP criterion
so that more or fewer EPs are recognized, you can trigger the re-
evaluation under Results with [Recalculate].
For dynamic equivalence point titrations you can also show the ERC in
addition to the titration curve. If the difference between the ERCs of the
endpoints is large enough you will also be able to read off a sensible
value for the EP criterion from the curve.