A new sensitive isothermal titration microcalorimeter using polyvinyli
dene difluoride (PVDF) as detector has been developed. Heat pulses of
less than 0.4 mu J can be detected and the baseline noise level (p-p)
is 40 nW. The calorimeter is constructed with one reaction cell (0.7 m
l) insulated by several radiation shields inside a vacuum chamber. The
performance of the instrument was examined by measuring the heat of p
rotonation of Tris with HCl. The enthalpy of reaction was found to be
-49+/-1 kJ.mol(-1), in good agreement with the reported value of -47.5
kJ.mol(-1).