鋳鉄中微量鉛の光度定量法

抄録

The existing method for the direct photometric determination of small amounts of lead in cast iron by dithizone extraction involves the warming of the solution with NH₂OH·HCl, Rochelle salt and KCN, for masking Fe(III) present as the principal constituent,but this warming may cause variable results due to imcompleteness of the masking. The authors herein show an accurate procedure in which the warming of the solution is avoided by first reducing Fe(III) with NH₂OH. HCl at the pH 2.5∼3.0 and then adding Rochelle salt and KCN. One extractoin is effective enough by using C₆H₆ instead of CHCl₃ or CCl₄ as solvent of dithizone even in the presence of large amounts of Fe. The proposed method is suitable for cast iron and also carbon steel containing 0.0003 to 0.04% of Pb.