Method for the analysis of impurity contents in silicon dioxide

Abstract

An analytical method for the quantitative determination of the impurities in silicon dioxide by which trace amounts of hardly soluble impurities contained in silicon dioxide can be reliably decomposed and converted into a solution so that the contents of all of the impurities contained in silicon dioxide or, in particular, zirconium in a natural quartz powder can be accurately determined. Silicon dioxide is decomposed with hydrofluoric acid or an acid mixture of hydrofluoric acid and another inorganic acid to give a decomposition solution which is, as such or after admixture with another inorganic acid, subjected to evaporation to dryness and the residue is heated to cause fusion with addition of a salt or hydroxide of an alkali metal followed by dissolution of the salt or hydroxide of an alkali metal with pure water or with an aqueous solution of an inorganic acid to give an aqueous solution which is subjected to quantitative analysis of the impurities therein.