臭化物-MIBK抽出を利用した原子吸光分析法によるクロム定量

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The determination of chromium was carried out by atomic absorption spectrophotometry combined with an extraction method. Chromium(VI) was extracted from an aqueous solution of sulfuric acid-potassium bromide. More than 90% of chromium(VI) was extracted with methylisobutylketone (MIBK) from the solution of 0.5 M KBr2N H2SO4, and 89% of chromium(VI) was constantly extracted from the solution of 210 N H2SO4-0.4 M KBr. Iron decreased the rate of extraction of chromium(VI), but this effect was masked by the addition of 2 g of Na4P2O7·10 H2O, if the concentration of iron was less than 500 ppm. Neither the presence of copper and cobalt (each<500 ppm) and nickel (<250 ppm) nor of aluminum, zinc, manganese(II), and magnesium at 1000 ppm affected the rate of extraction. Under the same condition of extraction tin, copper, zinc, and manganese(II) was extracted, but aluminum, cobalt, iron, nickel, and silver did not. Thus, chromium could be determined by using a fuel-rich flame with high sensitivity without being interferred by the presence of several common cations. By the aid of the MIBK extraction the sensitivity was increased to (0.05 μg/ml)/1%, which was as much as eight times that obtained by using aqueous solution. The present method was satisfactorily applied to the determinaition of trace chromium in an aluminium alloy. The determination of chromium was made a Hitachi model 207 spectrometer and the working conditions were as follow: the wavelength, 3579Å; the current of the hollow cathode lamp, 9 mA; the slit width, 0.18 mm; air pressure, 1.8 kg/cm2 (13 l/min) ; acetylene pressure, 0.5 kg/cm2 (2.5 l/min) ; position of burner, 1.5 mm from beam. The recommended procedure: Dissolve 0.5 g of sample with 20 ml H2O, 10 ml HNO3, and 3 ml H2SO4 in a 200 ml beaker, and heat until the fume of sulfuric anhydride is evolved. After cooling add 3040 ml of water, and boil to dissolve the content. Cool the solution and transfer it into a 100 ml measuring flask, and dilute to the mark with water. Take an aliquot containing 0.020.04 mg of chromium, add 1.2 ml of H2SO4, and dilute to about 20 ml with water. Add 23 drops of 2% KMnO4 solution and boil for 12 minute. Cool with water, transfer the solution into a separatory funnel, add 2 g of Na4P2O7-10 H2O (powder) and dissolve, and dilute the solution to 20 ml with water. Add 4 M KBr drop by drop until the color of KMnO4 disappears, add further 2 ml of 4 M KBr solution. Shake the solution for 4060 second with 10 ml of MIBK. Separate the organic phase, and measure the chromium in it with atomic absorption spectrophotometer against the reagent blank
社団法人日本分析化学会の論文

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河野隆年
岩手県工業試験場

臭化物-MIBK抽出を利用した原子吸光分析法によるクロム定量

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