User`s manual

14 Chapter 3: Theory of Operation
Calorimetry Sciences Corp.
CSC 5300 N-ITC III 15
User’s Manual
used to determine titrate concentration and/or ∆H for stoichiometric reactions. Non-linear
regression techniques are used to extract the equilibrium constant (K) as well as ∆H from
the thermogram for reactions that do not go to completion.
Applications
Batch/Incremental Titration
In incremental or batch
titration, one of the reactants
is placed in a syringe or bu-
rette external to the reaction
vessel. If individual repeated
injections are made, incremen-
tal titration takes place (as in
the example in Figure 3-2); if
only one injection is made it
is batch injection calorimetry.
This generic designation in-
cludes direct injection enthal-
pimetry (DIE).
The baseline data, i.e. heat
ow in the regions before
and after each titrant pulse, in
Figure 3-3 shows the rate of
heat loss or gain of the reaction vessel and its contents in the absence of any reaction.
The baseline in this region is a function of heating by stirring, and, in the case of an
unsealed vessel, evaporation or condensation. The baseline is used to calculate the area
or the heat from each pulse in the reaction vessel during the titration or batch reaction.
The thermogram constructed from the integrated peak areas (Figure 3-4) is used for data
analysis as described below.
Figure 3-2: Heat ow versus time for an experiment in which
a dilute solution of 2’CMP is incrementally titrated into a
dilute solution of RNase A.