Loss on ignition

Loss on Ignition is a test used in inorganic analytical chemistry, particularly in the analysis of minerals. It consists of strongly heating ("igniting") a sample of the material at a specified temperature, allowing volatile substances to escape, until its mass ceases to change. This may be done in air, or in some other reactive or inert atmosphere. The simple test typically consists of placing a few grams of the material in a tared, pre-ignited crucible and determining its mass, placing it in a temperature-controlled furnace for a set time, cooling it in a controlled (e.g. water-free, CO₂-free) atmosphere, and redetermining the mass. The process may be repeated to show that mass-change is complete. A variant of the test in which mass-change is continually monitored as temperature is changed, is thermogravimetry.