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:

  1. Determine the amount of volatiles in your material: residual water or/and solvents.
  2. Assess the strength of the volatile bonding into the material.
  3. Calculate the stoichiometry of a solvate/hydrate.
  4. Interpret the DSC data.
  5. Study oxidative stability by determining the oxidative-induction time (OIT) or oxidation-onset-temperature (OOT) of a sample.
  6. Study other chemical reactions: decomposition, pyrolysis, etc.
  7. Determine loss on drying on a minimal amount of material.
  8. Analysis of ash and minerals.
  9. Determine the elucidation of structure in combination with other analytical techniques.
  10. Identify polymorphic forms in combination with XRPD and DSC.
  11. 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. 

InstrumentsMettler Toledo TGA 2
USP/Ph. Eur.USP 831/Ph. Eur. 2.2.34.
Temperature rangeRT-1100 °C
Resolution1 ug
Default parametersProtective gas: Air, 20 ml/min
Sample amount5-10 mg

OR

Consult our Experts

Dr. Wenbo Wang
QC Chemist

Dr. Anna Shevchenko
Principal Scientist

Literature

Elomaa M, Asplund T, Soininen P, Laatikainen R, Peltonen S, Hyvärinen S, Urtti A (2004) Determination of the degree of substitution of acetylated starch by hydrolysis, 1H NMR and TGA/IR. Carbohydr 57(3): 261-267.

Hsieh W H,  Cheng W T, Chen L C, Lin S Y (2018) Non-isothermal dehydration kinetic study of aspartame hemihydrate using DSC, TGA and DSC-FTIR microspectroscopy. Asian J Pharm Sci 13 (3):212-219.

Jurczak E, Mazurek AH, Szeleszczuk Ł, Pisklak DM, Zielińska-Pisklak M (2020) Pharmaceutical Hydrates Analysis—Overview of Methods and Recent Advances. Pharm 12(10):959.

Nguyen D H, Rimdusit N, Tran QT, Phan M Q, Vu T N, Nguyen TN, Nguyen TH, Rimdusit S, Ougizawa T, Tran T T (2021) Improvement of thermal properties of Vietnam deproteinised natural rubber via graft copolymerisation with styrene/acrylonitrile and diimide transfer hydrogenation. Polym Adv Technol 32(2):736-47..

Pyramides G, Robinson J W, Zito S W (1995) The combined use of DSC and TGA for the thermal analysis of atenolol tablets. J Pharm Biomed 13 (2):103-110.

Saad A E-S, Mostafa ME (2014) Pyrolysis characteristics and kinetic parameters determination of biomass fuel powders by differential thermal gravimetric analysis (TGA/DTG). Energy Convers Manag (85):165-172.

Schirmer J, Kim J S, Klemm E (2001) Catalytic degradation of polyethylene using thermal gravimetric analysis and a cycled-spheres-reactor. J Anal Appl Pyrolysis 60 (2): 205-217.

Yu J, Wang P, Ni F, Cizdziel J, Wu D, Zhao Q, Zhou Y (2019) Characterisation of microplastics in the environment by thermal gravimetric analysis coupled with Fourier transform infrared spectroscopy. Mar Pollut Bull 145:153-60.

Zambrano Arévalo AM, Castellar Ortega GC, Vallejo Lozada WA, Piñeres Ariza IE, Cely Bautista MM, Valencia Ríos JS (2017) Conceptual approach to thermal analysis and its main applications. Prospectiva 15(2):117-125.

Zhang C, Kersten KM, Kampf JW, Matzger AJ (2018) Solid-state insight into the action of a pharmaceutical solvate: structural, thermal, and dissolution analysis of indinavir sulfate ethanolate. J Pharm Sci 107(10):2731-2734.

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