In analytical chemistry, ash is the name given to all non-aqueous residue that remains after a sample is burned, and consist mostly of metal oxides.
Ash is one of the components in the proximate analysis of biological materials, consisting mainly of salty, non-organic constituents. It includes metal salts which are important for processes requiring ions such as Na+ (Sodium), K+ (Potassium), Ca2+ (Calcium). It also includes trace minerals which are required for unique molecules, such as chlorophyll and hemoglobin.
For instance, the analysis of honey shows:
In this example the ash would include all the minerals in honey.
Also see: