PURPOSE: To separate matrix completely, to capture a minute amount of phosphoric acid quantitatively and to perform determination with excellent accuracy by approximately the same preprocessing method even for any of recovered nitric aid and radioactive organic solvent.
CONSTITUTION: When the quantity of recovered nitric acid sample solution is determined, alkaline aqueous solution is used, and hydrogen-ion concentration is adjusted to the pH value of 3-6. Then, zinc oxide powder is added. When the quantity of sample solution comprising radioactive organic solution is determined, the zinc oxide powder is directly added without the adjustment of pH, and the solvent is brought into contact with the zinc oxide powder with a magnetic agitator and the like. Thus, phosphoric acid is quantitatively captured, and insoluble residue can be formed. As the alkaline aqueous solution used in the pH adjustment of the recovered nitric acid sample solution, sodium carbonate aqueous solution, sodium hydroxide aqueous solution, ammonium hydroxide and the like are preferable. Of these, the sodium carbonate aqueous solution is optimum. After the insoluble residue is filtered and separated, concentrated nitric acid is added, and the residue is made to be solution. For the solution, it is preferable that phosphor is determined by chemical analysis and absorptiometry. The phosphoric acid can be determined at the level of ppm espetially by heteropoly-blue absorptiometry (chemical analysis).
OZEKI NOBORU
KUNO KOJI
AONO KAZUYOSHI
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