ISO 8215:1985

Surface active agents — Washing powders — Determination of total silica content — Gravimetric method

From a test portion all ethanol-soluble matter is removed by extraction with ethanol. The solution of the ethanol-insoluble residue is treated with hydrochloric acid and evaporated to dryness. The residue is dissolved in water and the operations are repeated twice. From the solution obtained after this operations the precipitate is filtered, washed, heated to 900 °C and weighed.