Indium (calibration standard, purity > 99.999 %)
Standard for calibration
Measuring cell: DSC821e
Pan: Alumina 40 µl, with pierced lid
Sample preparation: Indium pellet, pressed flat, premelted
DSC measurement: Heating from 120 °C to 180 °C at 10 K/min
Atmosphere: Nitrogen, 50 cm3/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, as in this case, the values lie within the allowed limits then the message ‘The DSC module is within specifications’ is displayed.
Measured | Ref. value | Tolerance | |
---|---|---|---|
Melting point (onset) | 156.75 | 156.60 | +/- 0.3 °C |
Heatr of fusion | 28.42 | 28.45 | +/- 0.6 J/g |
The so-called indium-check is a quick and easy method to check the temperature and heat flow calibration of an instrument. The results are automatically compared with reference values. The instrument displays the appropriate message if an adjustment of the instrument is required.
If the instrument is frequently used in other temperature ranges, then further checks with additional standards suitable for those temperature ranges are recommended.
The tolerances given in this example are standard values and can be individually adapted.
DSC Calibration, Temperature and Heat Flow | Thermal Analysis Application No. HB805 | Application published in METTLER TOLEDO TA Application Handbook Pharmaceuticals