METHOD FOR SEPARATING DETERMINING QUADRIVALENT SELENIUM FROM HEXAVALENT SELENIUM IN SOLUTION

摘要

PROBLEM TO BE SOLVED: To obtain a correct measurement value from a stable measurement result in a simple operation even when a content of Se⁶⁺ is minute to a content of S⁴⁺, by adding hydrochloric acid and nitric acid to a solution in which Se⁴⁺ and Se⁶⁺ are dissolved, heating and reducing the Se⁶⁺ to Se⁴⁺. ;SOLUTION: Se⁴⁺, Se⁶⁺ present in a solution are totally reduced to Se⁴⁺ and a total quantity of Se⁴⁺ in the solution is measured. A quantity of Se⁶⁺ is calculated from a difference of the measured total quantity of Se⁴⁺ and a quantity of Se⁴⁺ measured without a reduction process. In the reduction process, hydrochloric acid is added as a reducing agent to the solution containing the Se⁴⁺ and Se⁶⁺ and heated, whereby the solution is reduced to Se⁴⁺ and Se⁶⁺. At this time, since the Se⁴⁺ is reduced far to Se⁶⁺ to make determination difficult if a reduction process condition is too intensive, nitric acid having a reduction restriction effect is added thereby restricting a reduction reaction. An addition amount is approximately 35% hydrochloric acid and 61% nitric acid of the sample solution. Too little hydrochloric acid prevents the reduction from proceeding and too much hydrochloric acid forms Se⁰. Also too little nitric acid forms Se⁰ thereby lowering a recovery, while too much nitric acid hinders formation of hydride at an analysis time.;COPYRIGHT: (C)1999,JPO