METHOD OF ELEMENTARY ANALYSIS OF SILICIUM AND ALUMINIUM-CONTAINING COMPOUNDS Russian patent published in 1995 - IPC

FIELD: analytical chemistry. SUBSTANCE: weight of Silumin sample of mass 0.5 g is mixed with 1.5 g boric acid the aluminium:boric acid mass ratio being 1:3.1. The mixture is placed in the smaller 15 см³ chamber of the fluoroplastic two-chamber reaction vessel arranged in an analytical autoclave. The mixture is moistened with 0,3 cm³ concentrated hydrochloric acid 1,19 g/cm³ in density the solid-liquid ratio being 1:1.7. 25 cm³ of concentrated hydrofluoric acid with a density of 1,157 g/cm³. is poured in to the large chamber with a holding capacity of 600 cm³. The smaller reaction chamber is disposed in line inside the larger one. The two-chamber reaction vessel with contents is covered with a lid and pressurized in the metal shell of the analytical autoclave. The latter being positioned in an electric heater and held at 230 C for 4 h (hydrofluoric acid vapor concentration is 240 mg/cm³ with water concentration equaling 200 mg/cm³). The autoclave is cooled to a room temperature followed by depressurization and opening the reaction vessel. Its contents are dissolved in a diluted solution of hydrochloric acid and transferred to a polyethylene or fluoroplastic vessel. Electrochemical or atomic absorption elementary analysis of the solution is accomplished against a background of aluminium and accompanied by atomizing in the air-acetylene flame. EFFECT: more accurate results of analysis.