Thermogravimetric Analysis (TGA)
Thermogravimetric analysis, TGA, is used to show if a compound contains components such as solvents or other loosely bound molecules that might evaporate upon heating. The presence of solvents/hydrates is usually not desirable as these might cause destabilisation of the compound. Further, this method is used to distinguish between solvates and “pure” polymorphic forms.
The thermogravimetric analysis will help you to:
- Determine the amount of volatiles in your material: residual water or/and solvents.
- Assess the strength of the volatile bonding into the material.
- Calculate the stoichiometry of a solvate/hydrate.
- Interpret the DSC data.
- Study oxidative stability by determining the oxidative-induction time (OIT) or oxidation-onset-temperature (OOT) of a sample.
- Study other chemical reactions: decomposition, pyrolysis, etc.
- Determine loss on drying on a minimal amount of material.
- Analysis of ash and minerals.
- Determine the elucidation of structure in combination with other analytical techniques.
- Identify polymorphic forms in combination with XRPD and DSC.
- Study a kinetic of dehydration of a hydrate/solvate at different temperatures and under different conditions.
For Material Experts:
Instrument and measuring principle, TGA
TGA measures the amount of weight change of a material, either as a function of increasing temperature or isothermally as a function of time, in an atmosphere of nitrogen or air. TGA consists of a sample pan that is supported by a precision balance. The pan resides in a furnace and is heated or cooled during the experiment, and the mass of the sample is monitored during the experiment. The balance can register weight changes of down to 1 µg.
TGA determines the temperature and weight change of decomposition reactions, which allows quantitative composition analysis. It may be used to determine water/solvent content, either in the form of solvates or as loosely bound molecules on the particle surface. TGA can be used to measure evaporation rates, such as to measure the volatile emissions of liquid mixtures.
|Instruments||Mettler Toledo TGA 2|
|USP/Ph. Eur.||USP 831/Ph. Eur. 2.2.34.|
|Temperature range||RT-1100 °C|
|Default parameters||Protective gas: Air, 20 ml/min|
|Sample amount||5-10 mg|