Instrumentation, HSDSC

The nature of HSDSC instruments allows experiments to be run incorporating both isothermal and scanning steps. This enables rapid screens for excipient compatibility. An example is provided by the study of aspirin with two excipients using HSDSC (41). Figure 10 shows the HSDSC trace obtained for a binary mixture of acetylsalicylic acid (aspirin) with lactose and Figure 11... 

The increase in sensitivity over standard DSC instruments and the ability to study reactions occurring in solution directly mean that HSDSC may be applied to the study of a range of systems not open to study by standard DSC. Typical examples include the denaturation of proteins, phase changes in lipid bilayers, phase transitions in dilute polymer solutions, and changes in structure of creams and emulsions. Although there are many systems that have been studied using HSDSC, the discussion that follows will concentrate on systems of biological or pharmaceutical relevance. 

Specifications and Applications for Some Commercial HSDSC Instruments... 

Irrespective of whether an instrument employs fixed cells or batch cells, some design considerations are common to all HSDSC instruments. To measure accurately small powers, it is necessary to ensure good baseline stability throughout the course of an experiment. This is usually achieved by maintaining very accurate control of the calorimetric block temperature and ensuring that the properties of the sample and reference cells, such as geometry, cell volume, local environment, thermal conductivity and conduction pathways, and heating rate, are identical. 

Some HSDSC instruments have the capability of running experiments with more than one sample simultaneously for example, the CSC 4100 (Calorimetry Sciences... 

HSDSC instruments that employ batch cells are capable of studying heterogeneous systems and, hence, can be used to directly study industrial products, such as creams, powders, or liquids. Perhaps the two most important areas in which HSDSC may be used industrially are stability testing and excipient compatibility. 

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