IMPROVED ANALYSIS OF ISOPERIBOL HEAT-PULSE CALORIMETRY

The post-heating temperature drift curve in isoperibal heat-pulse calorimetry with isothermal shields is correctly described by an exponential function. We have implemented this analysis in an extended form in a small-sample (less-than-or-equal-to 10(-2) mol) calorimeter with a 'tray-type' sample holder, when the external relaxation time constant is comparable to the heat-pulse duration. The analysis turned out to be particularly advantageous at temperatures above 100 K We obtained an average scatter of about 0.07% which is nearly five times lower than the normally used linear extrapolation method and yield absolute errors below 1%.