METHOD OF SPECTRUM ANALYSIS OF IMPURITIES Russian patent published in 1995 - IPC

FIELD: chemical engineering. SUBSTANCE: silicium sample is mixed with a ground fluoroplastic in the ratio of 2·10^-3:1. The sample is next placed in a graphite electrode crater. Added to the sample is a solution containing 1% by weight of complexing agent in the form of brilliant green in the ratio of 5·10^-3:1 and a solution containing 100% by weight of potassium periodate as oxidizer the solution:sample ratio being 5·10^-2:1. The sealed fluoroplastic chamber provided with an electrode and holding a mixture of hydrofluoric acid mixed with nitric one is placed in an electric heater and left to stand at 200 C for 2 h. After keeping at a room temperature for cooling the electrode is withdrawn from the chamber and subjected to a spectrum analysis for the presence of impurities. Fluoroplastic and complexing agent can be chosen out of the group containing mannitol, glycerin, trityl chloride, dianiline and butyl rhodamine. The oxidizer is chosen out of the series comprising potassium permanganate, chlorobutyric acid, hydrogen peroxide, nitric acid, potassium periodate. EFFECT: analyzing boron, phosphorus and arsenic impurities. 4 cl