Question

How do you calibrate a DSC?

Answer 1

Calibration of a DSC is important for the traceability and uncertainty of thermal measurements.

Indium pellet, pressed flat are used as sample (Sample preparation).

DSC experiments were performed under continuos nitrogen flow at 50 cm³/min and heating the sample from 120 °C to 180 °C at 10 °C/min.

The DSC curve shows the melting of indium. A pure substance melts at an exactly defined temperature, its melting point. The melting point is taken to be the start or onset of the melting process which is defined as the temperature given by the intercept of the extrapolated slope of the melting curve and the continuation of the base line.

The onset temperature and the heat of fusion of indium are determined. The fully automated evaluation performs a validation which compares the measured values with literature values. If, the values lie within the allowed limits then the message ‘The DSC module is within specifications’ is displayed.

Let;s take a random example for your understanding.

Measured Ref. value Tolerance

Melting point (onset) 156.75 156.60 +/- 0.3 °C

Heat of fusion 28.42 28.45 +/- 0.6 J/g