Dry ashing

Abstract

Dry ashing procedures use a high temperature muffle furnace capable of maintaining temperatures of between 500 and 600 oC. Water and other volatile materials are vaporized, and organic substances are burned in the presence of the oxygen present in the air to CO2, H2O and N2. Most minerals are converted to oxides, sulfates, phosphates, chlorides or silicates. Whilst most minerals have fairly low volatility at these high temperatures, some are volatile and may be partially lost, e.g. iron, lead and mercury. If an analysis is being carried out to determine the concentration of one of these substances, then it is advisable to use an alternative ashing method that uses lower temperatures.