Influence of the Heating Rate on Moisture Content Determination, an O/W Cream
Sample
O/W Cream sample 647-A
Application
Basic material for the manufacture of creams
Conditions
Measuring cell: TGA850
Pan: Aluminum 100 μl, with pierced lid. The lid was automatically pierced shortly before the measurement (sample changer with needle, 1 mm diameter)
Sample preparation: As received, no preparation
TGA measurement: Heating from 20 °C to 200 °C at 2 and 5 K/min. Both measurements are blank curve corrected.
Atmosphere: Nitrogen, 50 cm3/min
Interpretation
The TGA curves show the evaporation of the volatile components (mainly water) in the region between 40 °C and 140 °C. At higher heating rates the evaporation is diplaced to higher temperatures. The first derivative of the TGA curve is helpful for the determination of the final step of the TGA signal.
Evaluation
| Heating rate | Step % | Peak temperature DTG, °C |
|---|---|---|
| 2 K/min | 59.4 | 102.1 |
| 5 K/min | 58.5 | 122.4 |
Conclusion
The influence of the mass and form of the sample, the heating rate and the type of pan have to be considered when developing methods. The heating rate is of special importance when investigating time and temperature dependent effects such as evaporation.
Influence of the Heating Rate on Moisture Content Determination, an O/W Cream | Thermal Analysis Application No. HB814 | Application published in METTLER TOLEDO TA Application Handbook Pharmaceuticals