メタノール分析におけるアセトアルデヒドアンモニア添加の影響 : 19730522

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It was found that the oxidation of methanol to formaldehyde was accelerated by adding not only potassium permanganate-sulfuric acid but also an acetaldehyde-ammonia solution. By utilizing this fact the following procedure is proposed to the spectrophotometric determination of methanol. To oxidize 1 ml of the test solution containing 115 μg of methanol, add 0.1 ml of 0.4 mg/ml acetaldehydeammonia solution, 0.1 ml of 0.5 M sulfuric acid, and 0.1 ml of 0.012 g/ml potassium permanganate solution. Swirl the mixture, and keep it at room temperature for 10 minutes. Add 0.1 ml of 0.03 g/ml sodium sulfite solution to reduce the excess permanganate. Swirl the mixture, and add 0.2 ml of 0.02 g/ml aqueous chromotropic acid solution. Add slowly 4 ml of 75 v/v% sulfuric acid. Heat the mixture in a water bath at 8085°C for 10 minutes with occasional swirling. Upon cooling to room temperature, measure the absorbance at 575 nm against the reagent blank obtained by the same procedure as described above. The calibration curve follows Beers law in the range 115 μg/ml of methanol. The molar extinction coefficient is 7.2 × 103. The ratio of the oxidized amount of methanol to formaldehyde is 48%. Oxidation of methanol is accelerated by using propionaldehyde instead of acetaldehyde-ammonia. However it emits an offensive odor, which is the only defect of propionaldehyde.
社団法人日本分析化学会の論文