Method for production of standard oxide sample for X-ray fluorescence spectrometry

A method for producing a standard oxide sample for use in measuring the content of a known impurity element in an organic compound by X-ray fluorescence analysis, said method comprising the steps of:

• a. dissolving said inorganic compound in nitric acid, nitric acid and hydrochloric acid, or nitric acid and hydrofluoric acid to obtain an acid solution thereof;
• b. adding said known impurity element to said acid solution in a concentration in the range of from 1 to 2,000 ppm based on the concentration of said inorganic compound to obtain a mixed solution wherein said known impurity has been dissolved in the acid;
• c. evaporating said mixed solution to dryness to obtain a dry residue of evaporation;
• and
• d. heating said dry residue of evaporation up to 600.degree. C. to obtain said standard oxide sample containing said inorganic compound and said impurity.