エタノール添加によるメタノール比色定量の改良法

概要

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A sensitivity of spectrophotometric determination of methanol, as oxidized to formaldehyde with pottassium permanganate-sulfuric acid, was increased by adding an ethanol solution to sample solution. Based on this fact, the following procedure was proposed to the spectrophotometric determination of methanol with chromotropic acid. Add 0.1ml of 1.5% ethanol, 0.1ml of 0.25M sulfuric acid, and 0.2ml of 5% potassium permanganate solution to 1.0ml of the test solution containing (1〜15)μg of methanol. Swirl the mixture, and keep it at room temperature for 20 min. Add 0.3ml of 20% sodium sulfite solution to reduce the excess of permanoranate. Swirl the mixture and add slowly 4ml of 75% sulfuric acid. Add 0.3ml of 2% aqueous chromotropic acid solution. Heat the mixture in a boiling water bath for 10 min with occasional swirlings. Upon cooling to room temperature, measure the absorbance at 575nm against the reagent blank. The sensitivity of this procedure was about five times more than that of no ethanol procedure.
社団法人日本分析化学会の論文
1978-12-05