Differential Scanning Calorimetry (DSC)
DSC is suitable to examine all physical processes taking place during heating and cooling of a pharmaceutical compound, for example, melting point, stability of the compound, decomposition temperature etc. Determination of the thermal behaviour is a required part of the physical characterisation of a pharmaceutical compound.
Differential scanning calorimetry is highly relevant to:
- Determine melting point, desolvation, glass transition, heat capacity, sublimation or thermal decomposition point of your compound, for instance, as an ID method.
- Examine the stability of the compound, as transitions or melting at low temperature is not desirable.
- Evaluate the relative stability of different crystalline forms to study transitions between states.
- Find out if the polymorphic forms are monotropic or enantiotropic.
- Evaluate crystallisation behaviour during heating – which might, for instance, lead to new polymorphic forms.
- Comparison of batches. Differences in energies upon melting might be due to amorphous material impurities or content, i.e. for evaluation of batch-to-batch variation.
- Purity evaluation by freezing point depression and applied for intermediates, raw materials, and final drug substances.
- Quantify and qualify the presence of the small amount of amorphous phase in a crystalline sample.
- Study stability of amorphous drug substances.
- Predict stability/instability of amorphous solid dispersions.
- Screen for co-crystals and polymorphs.
- Study phase diagram. Describe the type of enantiomer/stereoisomer/diastereomer mixture – compound or racemate.
- Study drug-excipient compatibility.
- Study oxidative stability by determining the oxidative-induction time (OIT) or oxidation-onset-temperature (OOT) of a sample and other chemical reactions.
- Perform safety screening—the presence of an exothermic event to assess the stability of a substance to heat.
- Study of retardation of the glass transition temperature as a function of relative humidity to predict the stability of amorphous materials and amorphous solid dispersion.
- Search for the best polymer for amorphous solid dispersion.
- The thermodynamics analysis of proteins can reveal necessary information about the global structure of proteins and protein/ligand interaction.
Instrument and measuring principle DSC
Measure the temperatures and heat flow associated with transitions in materials as a function of time and temperature in a controlled atmosphere.
A small amount of sample is needed. Differential scanning calorimetry measures the amount of energy (heat) absorbed or released when a specimen is heated, cooled, or held at a constant temperature.
The instrument applied by Particle Analytical is a Mettler DSC 823e Differential Scanning Calorimeter (DSC).
|Instrument||TA DSC2500 modulated DSC|
|USP/Ph. Eur.||USP 891/Ph. Eur 2.2.34 Thermal Analysis|
|Temperatures||-65 to 700 °C|
|Heating rate||Up to 20 °C/min|
|Sample amount||5-10 mg|
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