Metrohm tiamo 1.2 Manual - Handbuch (Seite 480)

454 Method
Gran evaluation
The Gran evaluation can be used to determine S-shaped DET and MET titration
curves. Two different procedures can be selected which are called
Normalized and
Standard .
In the normalized procedure, the titration curves are linearized in two parts. The
first part is before, the second after the equivalence point. The gran function G is
then poltted vs. the reagent consumption to get the Gran end point GP.
In the standard procecure, which is only available for DET pH und MET pH , only
the part before the equivalence point will be linearized. The Gran end point GP is
the intersection point of the curve before the equivalece point and the reagent
axis.
The Gran evaluation is only suitable for potentiometric titrations with one single
jump. Curves with several jumps can't be evaluated since all jumps are evaluated
together. You may wish this e.g. for great jumps with two equivalence points
which are close. In some cases you may wish to have such curves evaluated with
one equivalence point only, e.g. titrations of NaOH which contains carbonate.