パラタングステン酸アンモニウム中のカルシウムの定量

抄録

With regard to the determination of foreign elements in tungsten, cinchonine has been widely used as a precipitant of tungsten. This paper, however, deals with the flame-photometric determination of calcium in ammonium paratungstate (A. P. T.) by the following isolation procedure of tungsten. A. P. T. is dissolved in a mixture of conc. hydrochloric acid and hydrogen peroxide, and the solution is heated until the decomposition of hydrogen peroxide is completed, and tungsten is precipitated as hydrous tungsten oxide. Methyl alcohol is added to eliminate the adsorption of calcium on the precipitate, and to decrease the solubility of the precipitate, then the precipitate is filtered off, and calcium is analyzed flame-photometrically.