Determination of phosphoric and silicic acids in aqueous solution by high-speed liquid chromatography using solvent extraction of the molybdoheteropoly acid.

The procedure is as follows: Twenty-five ml of 0.25N nitric acid solution containing phosphoric and silicic acids is heated in a water bath of about 60℃, One ml of 5% ammonium molybdate is added to the solution, and the mixture is allowed to stand further for 5 min in the water bath. By this process, the molybdoheteropoly acid is formed. After cooling to room temperature, the aqueous solution is transferred into a separatory funnel together with 5ml of methyl propionate. Molybdophosphoric acid is selectively extracted into the organic chase by shaking for 10 min. Then the aqueous phase is equilibrated with 5ml of methyl isobutyl ketone. By this process, molybdosilicic acid is extracted into the organic phase. After centrifuging to remove water suspended in the both organic phases, the molybdoheteropoly acid is determined by high-speed liquid chromatography with a ultra-violet spectrophotometric detector. Phosphoric acid ranging from (0.015～0.2) ppm (as phosphorus) and silicic acid ranging from (0.15～2) ppm (as silicon) in aqueous solution can be determined rapidly by this method.rights: 社団法人日本分析化学会rights: 本文データは学協会の許諾に基づきCiNiiから複製したものであるrelation：isVersionOf: http://ci.nii.ac.jp/naid/110002910161