ヘテロポリ青の1-ブタノール抽出による高純度水中の微量ケイ酸イオンの吸光光度定量

概要

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To determine trace silicate in highly purified water, conditions for the extraction of Heteropoly Blue into 1-butanol were investigated. A sulfuric acid concentration of 1.3 M was proposed for the extraction. The recommended procedure is as follows. Two bundred milliliters of a sample solution is taken in a 300 ml Teflon separating funnel and 4 ml of an ammonium molybdate (20%)-H_2SO_4 (2.5 M) solution is added. The solution is left standing for 20 min to form molybdosilicic acid completely. After the addition of 25 ml of H_2SO_4 (2+1) and 2 ml of L-ascorbic acid solution (10%), it is left standing for 10min to develop Heteropoly Blue. Twenty five milliliters of 1-butanol is added to the solution which is shaken for 2 min. The absorbance of the Heteropoly Blue extracted into the organic layer is measured at 800 nm. For the reagent blank test, 4 ml and 8 ml of the ammonium molybdatee-H_2SO_4 solution are added respectively to two 200 ml portions of water. The absorbances, A_1 and A-2,for the two solutions are measured as mentioned above. The difference. A_2-A_1,corresponds to the absorbance due to 4 ml of the ammonium molybdate-H_2SO_4 solution. The absorbance obtained on a sample is corrected by subtracting the A_2-A_1 value. Silicate in some highly purified waters was determined to be over the range of 2〜25 μg of SiO_2/l.
社団法人日本分析化学会の論文
1990-08-05