DSC Balances Out

摘要

Differential scanning calorimetry (DSC), like the closely related technique of differential thermal analysis (DTA; see the Product Review in the Oct. 15, 1994, issue [Anal. Chem. 1994, 66, 1035 A-1038 A]), is an established method with roots that stretch back to the days of Lavoisier and his ice calorimeter. Modern calorimetry finds applications in the pharmaceutical, food and beverage, and polymer industries as well as in research areas such as metabolism and catalyst characterization. DTA measures the difference in temperature between a sample and a thermally inert reference material when both are heated according to the same program. In power compensation DSC, the temperature of the sample is constantly adjusted to match that of the thermally inert reference material as the temperature range is scanned. In heat flux DSC, heat flow is determined from the differential temperature across a fixed thermal path between the sample and a reference. All three methods can provide quantitative values for enthalpy and heat capacity. Aside from energy profiles, specific types of information that can be extracted from the data include phase transition temperatures, percent crystallinity in polymers, and food or pharmaceutical shelf life and stability.