Hach-Lange TITRALAB 840_845 Reference Manual - Manual (Page 96)

Titra Lab ® TitraLab 840 and 845 Reference Manual
Page 96
Equivalent point
determination
(IP methods) An equivalent point of a titrated species/titrant reaction is determined
in two ways depending on the titrant addition mode (continuous or
incremental) selected:
Continuous addition of the titrant (Continuous IP method):
• acquisition of the titration curve E (electrode) = f (volume of titrant
dispensed),
• calculation of the first derivative curve with smoothing process
(method parameter: smoothing criterion),
• determination of the second derivative curve,
• determination of the inflection points on the first derivative curve
from the minimum and maximum of the second derivative curve,
• determination of the tangents to the first derivative curve for these
inflection points,
• determination of the equivalent point as the intersection of the two
tangents.
Figure 17: Determination of an equivalent point - Continuous IP method
An equivalent point is determined and plotted live on the titration
curve. The method can be stopped after a given number (1 to 4) of
equivalent points has been detected.
E or pH