Thermogravimetric, or thermal, analysis (TGA or TG) measures changes in sample weight in a controlled thermal environment as a function of temperature or time. The changes in sample weight (mass) can be a result of alterations in chemical or physical properties and can be detected to a fraction of a microgram. TGA is useful for investigating thermal stability of solid or liquid materials under conditions of ramping temperature in an inert gas atmosphere or in an oxidative gas atmosphere. TGA can also be conducted at constant temperature to evaluate thermal stability of materials over a specific time period. For example, potential VOC emission from pesticides can be measured at constant temperature for determining the amount and rate of mass loss over a specified time period.

Coupling the TGA to a spectrophotometer allows the study of volatile species and pyrolysis products, which can lead to discovering how a compound or formulation degrades and what components it contains. For example, TGA coupled with mass spectroscopy (MS) can provide specific information on chemical structure for identifying additives, contaminants and composition of blends and copolymers (TGA-EGA).