交流ポーラログラフ法によるガソリン中のマンガンの定量

概要

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An alternating current polarographic method for determining manganese present in commercial gasolines as (methylcyclopentadienyl) manganese tricarbonyl is described. A 5ml sample of gasoline is treated with an excess of 30% solution of bromine in carbon tetrachloride to decompose organo-manganese compound. After decomposition, manganese is extracted by shaking the organic phase with 50 ml of 0.1 F nitric acid for 6 minutes. The extract is neutralized with 1 F potassium hydroxide, and 8ml of 50% triethanolamine and 12.5 ml of 4 F potassium hydroxide are added to it as supporting electrolytes, and finally the resulting solution is brought up to 100 ml with water. By passing air through it at a temperature of boiling-water bath, manganese is oxidized to manganic state. The alternating current polarogram is recorded and manganese is determined by a standard addition method. Five determinations on a sample of gasoline gave the average of 411.3 ppm of manganese with 1.52% of coefficient of variation. The present method is rapid compared with the conventional one and the time required is 40 minutes per sample.
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