ジフェニルカルバジドを用いた吸着ストリッピングボルタンメトリーによる鉄鋼中クロムの定量

概要

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A sensitive and selective method is described for the determination of chromium at the low ppm level in iron and steel by differential pulse adsorptive cathodic stripping voltammetry with diphenylcarbazide as complexing agent. The complex of chromium (VI) with diphenylcarbazide, Cr (III)-diphenylcarbazone, was adsorbed on a graphite electrode for 5 min with open circuit in a nitric-sulfuric acids mixture solution containing phosphoric acid (pH=ca. 0.6), and subsequently was stripped in another solution (the acid mixture solution in the absence of iron (III) and phosphoric acid) in the potential range 0.3 to -0.1V vs. SCE at a scan rate of 50 mV/s. Most of the foreign metals did not interfere by application of the non-electrolytic accumulation step. The calibration curve was linear over a concentration range 9.6×10^<-8> to 1.3×10^<-6>M of chromium (correlation coefficient >0.999) and passed through the origin. The detection limit (3σ) was 2.7×10^<-8>M (1.43ngCr(VI)/ml) for an accumulation time of 5 min. The determination of 8 to 500 massppm of chromium in iron and steel was achieved with good precision and accuracy within 1 h by the proposed method without any separation of the matrix. The simple method developed can be also applied to the determination of chromium in obsolete steel scrap.
社団法人日本鉄鋼協会の論文