Ash (analytical chemistry)

In analytical chemistry, ashing is the process of mineralization for preconcentration of trace substances prior to chemical analysis. 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, inorganic 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.

Example

For instance, the analysis of honey shows:

Typical honey analysis

• Fructose: 38%
• Glucose: 31%
• Sucrose: 1%
• Water: 17%
• Other sugars: 9% (maltose, melezitose)
• Ash: 0.17%

In this example the ash would include all the minerals in honey.

See also

• oxides, e.g. Al₂O₃, CaO, Fe₂O₃, MgO, MnO, P₂O₅, K₂O, SiO₂
• carbonates: Na₂CO₃ (aka soda ash), K₂CO₃ (aka potash),
• bicarbonates, e.g. NaHCO₃ (aka baking soda),

• Sulfates: sulfate ash according to Ph. Eur.