A new method for separation and spectrophotometric determination of phosphate ion by the liquid-liquid extraction with benzophenone at an elevated temperature

Summary A new type of separation of phosphate ion, along with its spectrophotometric determination, was established by liquid-liquid extraction, where the yellow heteropoly acid formed by the reaction with ammonium molybdate in acid solution is quantitatively extracted into molten benzophenone at a temperature of about 60° C. When cooled down to room temperature, the benzophenone extract converts from the liquid state to the solid state. The resulting solidified extract is dissolved in methyl propionate, and the phosphate ion in the solvent is determined spectrophotometrically by the blue heteropoly acid method. Possible interference by Si, As and Ge is eliminated by the separation procedure.The authors wish to thank President Dr. Yawara Yoshitoshi and Prof. Yoshisaburo Ota of University School of Medicine, for their hospitality and encouragement.