Creams with the following compositions (in %)
Sample | A | B | C | D | E |
---|---|---|---|---|---|
Oleyl alchohol | 10 | 10 | - | - | - |
Mygliol 812 | 15 | 15 | |||
Cetyl alcohol | 4 | 4 | 44 | 22 | 5.8 |
Stearyl alcohol | 4 | 4 | 44 | 22 | 5.8 |
Glyceryl monostearate | 2 | - | - | - | 2.9 |
Lanette E | 1 | 1 | 11 | 5.5 | 1.5 |
Benzyl alcohol | 1 | - | - | - | - |
Propylene glycol | 5 | 5 | |||
NaOH | 0.02 | 0.02 | - | - | - |
Citric acid | 0.05 | 0.05 | - | - | - |
Water | 57.93 | 59.93 | < 1 | 50 | 83.8 |
Basic materials for the manufacture of creams
Measuring cell: TGA850
Pan: Aluminum 100 µl, the lid was pierced, diameter of hole 1 mm
Sample preparation: As received, no preparation
TGA measurement: Heating from 20 °C to 200 °C at 2 K/min, blank curve corrected
Atmosphere: Nitrogen, 80 cm3/min
All the creams, with the exception of sample C, show a significant weight loss in the range 30 °C to 140 °C. This is caused by the evaporation of volatile components, above all water.
The individual steps are evaluated using the TGA curves
Sample | Step % | Inflection pt °C | Evaluation range °C |
---|---|---|---|
A | 60.6 | 96.1 | 20 - 161 |
B | 62.7 | 92.7 | 20 - 153 |
C | 0.53 | - | 20 - 146 |
D | 51.8 | 91.4 | 20 - 149 |
E | 84.4 | 97.8 | 20 - 131 |
The results lie slightly higher than the values expected from the specified water content. This can be explained by assuming that other volatile components evaporate and in this way cause a weight loss that is greater than expected.
Quantification, O/W Creams with Different Water Content | Thermal Analysis Application No. HB839 | Application published in METTLER TOLEDO TA Application Handbook Pharmaceuticals