Precise determination of melting and boiling points by differential thermal analysis and differential scanning calorimetry

Abstract

The theory, operation and instrumentation of differential thermal analysis (DTA) and differential scanning calorimetry (DSC) are sufficiently well developed to determine melting and boiling points with a high degree of certainty and reproducibility. However, certain precautions must be taken if data of maximum value are to be obtained. Sampling techniques, encapsulation, instrumental parameters and theoretical considerations will be treated in detail. In addition to the very small amount of material required for a melting or boiling point determination, DTA and DSC have other advantages. If certain precautions are observed it is possible to use several equations from classical thermodynamics to obtain absolute purity. A complete Cox Chart of a pure liquid can be obtained and the heat of vaporization determined in a few hours. Complex solid phase diagrams are easily studied. The success or failure of fractionation techniques can be predicted from single thermograms if several phase transitions are present. © 1973.