Moisture, Starch/NaCMC (Primojel)
Sample
Mixture of Na-CMC and potato starch (Primojel), water content approx. 6%
Application
Primojel consists of Na-CMC and potato starch and is able to take up over 40% of its weight in water. This capacity to take up water leads to its use as a disintegrating agent for tablets.
Conditions
Measuring cell: TGA850
Pan: Aluminum 100 μl, with pierced lid
Sample preparation: As received, stored under different conditions
TGA measurement: Heating from 30 °C to 300 °C at 20 K/min, blank curve corrected
Atmosphere: Nitrogen, 80 cm3/min
Interpretation
The samples lose their moisture at about 120 °C. The extent of the moisture-loss depends on the actual storage conditions. The higher the relative humidity and the longer the storage time, the greater the amount of water absorbed.
Evaluation
| Storage conditions | Step, % |
| 7 days over P2O5 | 3.4 |
| 1 days over P2O5 | 3.4 |
| As received | 5.6 |
| 1 day at 95% rel. humidity | 24.8 |
| 7 days at 95% rel. humidity | 41.3 |
Conclusion
The influence of the storage conditions must be taken into account when characterizing samples that are sensitive to moisture.
Moisture, Starch/NaCMC (Primojel) | Thermal Analysis Application No. HB824 | Application published in METTLER TOLEDO TA Application Handbook Pharmaceuticals