Metrohm 848 Titrino plus - Manual (Page 88)

7.1 Dynamic equivalence point titrations (DET)
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848 Titrino plus
first
Only the first equivalence point will be recognized.
greatest
Only the equivalence point with the greatest ERC value, i.e. the steep-
est jump, will be recognized.
last
Only the last equivalence point will be recognized.
Fixed EP1 at
The associated volume will be interpolated from the measuring point list
for the measured value entered. The fixed endpoint must lie between the
first and the final entry in the measuring point list.
Measuring mode pH:
Input range
–20.000 - 20.000
Selection off
Default value off
Measuring mode U, Ipol:
Input range
–1250.0 - 1250.0 mV
Selection off
Default value off
Measuring mode Upol:
Input range
–125.00 - 125.00 µA
Selection off
Default value off
Fixed EP2 at
See Fixed EP1 at.
Evaluation and equivalence point criterion with DET
The equivalence points (EP) are localized in a way similar to the Tubbs
method [1][2]. The volume value of the equivalence point (V
E
) is shifted
from the point of inflection (see arrow) towards the smaller circle of curva-
ture for real asymmetric titration curves.
[1] C. F. Tubbs, Anal. Chem. 1954, 26, 1670–1671.
[2] E. Bartholomé, E. Biekert, H. Hellmann, H. Ley, M. Weigert, E. Weise,
Ullmanns Encyklopädie der technischen Chemie, Bd. 5, Verlag Chemie,
Weinheim, 1980, S. 659.