改良型燃焼フラスコを用いる有機イオウの微量定量 : フラスコ燃焼法による有機元素分析(第2報)

概要

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(1) Structure of the combustion flask. The volume of the measuring pipet was reduced to 15 ml so that the washing solution could be supplied at once into the flask. The platinum basket was made smaller and a portion of platinum wire was replaced by copper to minimize the amount of platinum. (2) Determination of sulfur with Arsenazo III as an indicator. The sample is put in a gelatin capsule. The titration of sulfate using Arsenazo III indicator had a disadvantage of retardation of color change at the end point, but it was removed by titrating the test solution under the nearly unhydrous state. A mixed solution of Ba2+ and Pb2+ was recommended as the titrant, by which the color changed distinctly from red-violet to blue and satisfactory analytical values of sulfur were obtained. The time required for an analysis was 67 min.