Thermogravimetric Analysis

Themographic Analysis Diagram

Thermogravimetric Analysis (TGA) (Conducted in a Nitrogen Environment) involves the determination of the change in mass of a sample as a function of temperature and/or time of heating.  The TGA instrument used at Particle Technology Labs is a Netzsch TG 209 F3 Tarsus.  This instrument has been qualified for use from ambient temperature to 1000 °C and is capable of taking measurements using just a few milligrams of sample. 

The TGA instrument at Particle Technology Labs has been qualified in compliance with: U.S. Food and Drug Administration’s (FDA) current Good Manufacturing Practices (cGMP) Regulations, 21 CFR Parts 210 and 211 and the United States Pharmacopeia (USP), General Chapters  <891> Thermal Analysis and <1058> Analytical Instrument Qualification.  When applicable, samples are analysed per various methods including ASTM D3850, ASTM E2402, ASTM E1131, ISO 11358, ISO 7111, and USP <891>.

The most common analyses requested in a TGA are to determine:

  • degree of hydration
  • level of residual solvent
  • temperature at which a sample thermally decomposes

In most cases, surface adsorbed water can be differentiated from water within a crystal lattice as well as that of a non-aqueous solvent.  Many sample types undergo thermal decomposition as a function of temperature and furthermore, it is not uncommon for a sample to decompose in multiple steps. 

Another vital component of a TGA is the gas composition in the furnace.  Most commonly, a TGA is either performed in an inert nitrogen environment or in an oxidative environment of air.  In certain sample types, various pathways or mechanisms of degradation that may be present in an oxidative environment are not present in an inert environment.  Thus, the number of degradation steps and the temperatures at which the steps occur can be affected by the furnace environment.

Examples of studies suitable for a TGA include:

  • oxidative stability
  • thermal stability
  • compositional analysis
  • decomposition kinetics
  • catalyst activity
  • hydration content
  • solvent content
  • polymer and filler content
  • ash content 

Such studies have been applied across various industries, some of which include development and production of:

  • vaccines and pharmaceuticals
  • food ingredients
  • electronics
  • catalysts and scrubbers
  • batteries and fuel cells 
  • concrete and building materials
  • metals and alloys
  • plastics and polymers

Other areas that have been served by a TGA include the mining industry, as well as the fine particle sector including the analysis of silica, alumina, titania, zinc oxide, graphite, carbon black, graphene, and carbon nanotubes.