Thermogravimetric Analysis
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 or microliters of sample.
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 alloysplastics 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.
Advantages
- Determine volatilization or decomposition rate of materials
- Small amount of sample needed
- Rapid and accurate
Considerations
- Typical heating rates: 10 or 20 K per minute. Other ramp rates can be requested.
- Steady starting mass may be challenging to obtain for liquid samples
- The sample and decomposition products should not be corrosive
- Typical environment: nitrogen, though oxidative environment can also be requested
Sample Requirements
For dry materials, 5 mg minimum, prefer to receive 20 to 50 mg. For liquids, a minimum of 85 µL is required, 200 µL preferred.
Detection Range
This instrument has been qualified for use from Ambient Room Temperature to 1000°C.
Data Reported
The onset decomposition temperature, mass loss percent, and percent residual mass are provided along with a thermogram.
Sample Reports
Instrumentation
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 analyzed per various methods including ASTM D3850, ASTM E2402, ASTM E1131, ISO 11358, ISO 7111, and USP <891>.
