Differential scanning calorimetry purity determined using

NIRA provides a non-destructive alternative to differential scanning calorimetry for the determination of polymorphic forms of drugs, e.g. the polymorphic forms of caffeine. NIRA has also been used to determine optical purity. While the pure opposite enantiomers of a substance have identical NIR spectra, mixing two... 

Differential scanning calorimetry directly measures the heat flow to a sample as a function of temperature. A sample of the material weighing 5 to 10 g is placed on a sample pan and heated in a time- and temperature-controlled manner. The temperature usually is increased linearly at a predetermined rate. DSC is used to determine specific heats (Fig. 10-11), glass transition temperatures (Fig. 10-12), melting points (Fig. 10-13) and melting profiles, percent crystallinity, degree of cure, purity, thermal properties of heat-seal packaging and hot-melt adhesives, effectiveness of plasticizers, effects of additives and fillers (Fig. 10-14), and thermal history. 

High-purity materials are available as pure solids for chemical uses such as metals used as reference substances for metallurgical analysis, and compounds used as primary standards for many types of titrimetry, and as standards for elemental microanalysis. Other available high-purity substances intended for diverse physical properties include ion activity standards for the calibration of pH and ion-selective electrodes standards for various thermodynamic uses including melting point determinations, differential scanning calorimetry and bomb calorimetry and standards for the calibration of spectrophotometers. 

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