Differential Scanning Calorimetry

Intertek ASG Laboratory, Manchester, UK

State-of-the-art instrumentation offering DSC, Modulated DSC (MDSC) and Tzero DSC technologies

Intertek ASG has recently invested in a state-of-the-art TA Instruments Q1000 DSC which offers both MDSC and Tzero technologies. These new developments provide significantly improved performance in critical areas such as sensitivity, resolution and separation of complex transitions.

Differential Scanning Calorimetry (DSC)

DSC measures temperatures and heat flows associated with thermal transitions in a material. Common uses include investigation, selection, comparison and end-use performance evaluation of materials in research, quality control and production applications. Properties measured include:

Glass transitions
"Cold" crystallisation
Phase changes
Melting
Crystallisation
Product stability
Cure / cure kinetics
Oxidative stability

Modulated DSC (MDSC)

The benefits of MSDC over traditional DSC include:

Increased sensitivity
Increased resolution
Separation of complex transitions
More accurate measurements of crystallinity in semi-crystalline materials
Direct measurement of heat capacity (either while programming temperature or holding it isothermal)

These improvements over traditional DSC are achieved by applying two simultaneous heating profiles: a linear underlying rate similar to DSC plus a sinusoidally modulated rate. The linear rate provides the same information as traditional DSC while the modulated rate provides unique information about the sample's heat capacity.

Traditional DSC gives a single signal which is the sum of all thermal events occuring making it difficult to interpret the data or detect small transitions. With MDSC, both the total and the heat capacity components are recorded and the kinetic component is given by the difference between these. By separating complex transitions into these specific components, interpretation is greatly simplified.

Tzero DSC

The benefits of Tzero DSC over traditional DSC include:

Improved baseline performance
Increased sensitivity
Increased temperature resolution of transitions

These improvements result from a new cell design which produces two simultaneous differential measurements and enables the sensors to be individually calibrated for thermal resistance and heat capacitance as a function of temperature.

Pharmaceutical Applications of DSC

Thermal analysis has been an extremely important analytical tool within the pharmaceutical industry for many years. All trantisitons in materials involve the flow of heat (either into the sample during an endothermic event or out of the sample during an exothermic event) and DSC is the universal detector for measuring a wide variety of transitions in pharmacueutical materials. These include measurement of:

Amorphous Structure
- Glass transition
- Detection of amorphous material in semi-crystalline compounds
Crystallinity

Melting and crystallisation
Purity
Polymorphs

Drug - Excipient Interaction
Protein Denaturation
Freeze Drying

Automated Instrumentaton - Robotic Sample Handling

The new TA Instruments Q1000 DSC is a fully automated facility utilising robotic sample handling allowing rapid response to customer problems. The system is equipped with a 50 sample, 5 reference pan carousel tray, enabling samples to be run "round-the-clock". The state of the art modulated system offers improved understanding of complex thermal transitions and the sensitivity to investigate subtle thermal events such as protein denaturation or polymer glass transitions.

For further information on the TA instrument see: