ISO 5373:1981

Applicable to products having Ca contents equal to or more than 50 mg/kg. The presence of soluble SiO2 up to 5 g/ml in the test solution does not interfere. Hydrolysis by boiling a test portion in hydrochloric acid medium. Addition of sodium ions, until a constant concentration is obtained, to stabilize the promotion and emission of Ca; addition of lanthanum chloride to increase the sensitivity of the method. Aspiration of the solution into a dinitrogen monoxide-acetylene flame. Spectrometric measurement of the absorption of the 422.7-nm line emitted by a hollow-cathode calcium lamp. Has also been approved by the IUPAC.