PURPOSE: To prevent the scattering of a standard specimen when X rays are emitted and to perform measurement whose absolute value is stabilized for a long time by attaching fine powders of one or two or more kinds of metal oxides having a specified amount on a filter, and covering the powder with a macromolecular thin film.

CONSTITUTION: Metal oxides reagents shown in the Table are finely crushed. Specified amounts of the reagents are measured. The reagents are put into a measuring flask. Pure water is added, and the level is aligned with a marked line. The powders in the pure water are uniformly dispersed for 15-20min by using an ultrasonic wave cleaner, and a standard liquid is obtained. Then several-ml pure water is added on a specimen filter which is set on a filter device. The specified amount of the standard liquid which is prepared beforehand is accurately dispersed and dropped. After about 1min, filtering operation is performed. A macromolecular compound is blown on the capturing surface of the obtained metal oxide, and a protecting film is provided. The film is dried, and the standard specimen for fluorescent X rays is obtained. Since the metal oxide is used in the same pattern as an actual specimen, an analyzer can be calibrated accurately. The absolute value of the minute metal component in the actual specimen can thus be measured.