Butylated hydroxytoluene
Inactive ingredient (antioxidant)
Measuring cell: DSC821e with IntraCooler
Pan: Aluminum 40 µl, hermetically sealed
Sample preparation: As received, no preparation
DSC measurement: Heating from 50 °C to 80 °C at 2.5 K/min
Atmosphere: Air, stationary environment, no flow
The curves show the melting peaks as a function of sample weight. As expected, the peaks in the original presentation (ordinate in mW) increase in height but also in width with increasing weight. Because of this the resolution decreases. In contrast, the normalized presentation shows that the lowest sample weight gives the highest peaks.
The onset temperature and heat of fusion of the peaks are determined. The mean values of a number of measurements are presented in the table.
Sample weight | Onset, °C | Heat of fusion ΔH, J/g |
---|---|---|
18 +/- 0.3 mg | 69.4 +/- 0.1 | 85.6, 84.7, 85.6 |
8.5 +/- 0.3 mg | 69.6 +/- 0.1 | 83.9, 84.5 |
4.0 +/- 0.3 mg | 69.5 +/- 0.1 | 82.6, 84.1, 83.6 |
The sample weight influences the shape of the melting peak. The time required for melting is longer for larger samples because a greater amount of heat has to be transferred. As a result of this, the peaks are shifted to higher temperature. For comparison purposes, the measurement of samples of similar weight is recommended. Samples that are too large are disadvantageous: the peaks become broad (lower resolution) and non-uniform melting leads to irregularly shaped peaks.
Influence of the Sample Weight, Butylated Hydroxytoluene | Thermal Analysis Application No. HB817 | Application published in METTLER TOLEDO TA Application Handbook Pharmaceuticals