Spectrophotometric Determination of Copper in Titanium

Abstract

The chloroform-alcohol extraction of a copper(1) neocuproine complex has been used for the spectrophotometric determination of copper in titanium. Comparison photometric measurement permits determination on a 0.5-gram sample of 0.005 to 0.40% copper. Accuracy is within 470 with a coefficient of variation of 0.5 to 370, depending upon the level of absorbance. Chromium(ll1) is the sole metallic interference, and methods for the removal of this interference are presented.OMMERCIAL TITANIUM may contain C copper in amounts ranging from tenths of thousandths to several per cent, depending upon the type of material and its history. A method for determining copper in titanium is needed for application to the several orders of magnitude over which the concentration might range. None of the methods previously reported as applicable to titanium samples (6) meets such a requirement with speed or accuracy. Electrodeposition has been suggested (2), but a large sample is required, and preliminary separations must be made if common alloying agents used in titanium are present. Mikula and Codell (14) have reported a polarographic procedure for the simultaneous determination of copper, nickel, and cobalt; however, the useful concentration range is 0.2 to 5% for each of the components. A spectrophotometric method would probably be better suited to the broad range of copper concentrations which titanium materials present.Of the many color-forming reagents which have been proposed for the determination of copper, 2,Z'-biquinoline (5) and its structural analog, 2,g-dimethyl-1,lO-phenanthroline (neocuproine) , appear to be the most specific, most sensitive, and simplest to use. The excellent results obtained by Gahler (8) in the analysis of steels and by Crawley (' 7) on tungsten materials have prompted the selection of neocuproine for the present investigation.