Simultaneous Determination of Lead and Zinc in Iron and Steel by Cathode Ray Polarographic Method

概要

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In order to determine microamounts of lead and zinc in iron and steel, a highly sensitive and rapid cathode ray polarography was studied and the examinations were made of supporting electrolyte, treatment after removal of iron, effect of coexisting elements, and peak potentials. The method was then applied to iron and steel samples. In this method, the sample is decomposed with hydrochloric and nitric acids, which is evaporated to dryness, the residue is dissolved in 5N hydrochloric acid, and iron is extracted with methyl isobutyl ketone. A part of zinc that transited to the organic layer is back-extracted with 6N hydrochloric acid and this acid solution is mixed with the aqueous layer. This layer is evaporated to dryness, methyl isobutyl ketone is decomposed with nitric and perchloric acids, and the layer is again evaporated to dryness. This procedure is repeated three times. The cooled residue is submitted to polarography with 0.5M phosphoric acid as the supporting electrolyte, gelatin is added, and the wave height at peak potential is measured at -0.52 V vs S. C. E. for lead and at -1.17V vs. S. C. E. for zinc. This method enabled the determination of lead and zinc in synthetic and actual samples to the order of 0.00x%, the standard deviation being ±0.00017% for lead and ±0.00063% for zinc, and the coefficient of variation being 11.3% for lead and 15.1% for zinc.
東北大学の論文