This method is for determining the loss on ignition (LOI) in air, using a specified ignition temperature and time, for fresh, regenerated, used, and spent catalysts, catalyst supports, and molecular sieves of various shapes and sizes, including fines. This method is quantitative down to 0.1 mass-%. The method is not water specific, any components that volatilize at the selected ignition temperature, for example, carbon, chlorine, and fluorine, are also included in the LOI value. Some components, for example sulfates, may volatilize fully or partially depending on ignition time and temperature. Mass gains are possible with catalysts that contain reduced metals.

The criteria for selecting the temperature for the LOI are based on the volatility of components of materials. Examples are listed in procedure. Length of time at temperature is dependent on the application of the LOI values. For example, it is important to drive off defined volatiles, such as halogens, for the determination of platinum concentration.