Photometric determination of copper in iron, steel, nonferrous metals and alloys.

A simple and rapid photometric method for the determination of 0.0058% of copper in iron, steel, aluminum, zinc, tin, antimony, lead, magnesium and their alloys with biscyclohexanone oxalyldihydrazone (BCOD) has been established.Zinc and magnesium did not interfere. The interfering metals were removed or masked : iron and aluminum were masked with citric acid, lead was precipitated as lead sulfate, and tin and antimony were volatilized off as their bromide. The pH of the solution was then adjusted to 9.3 with ammonia water (1+1), and 12ml of ethyl alcohol and 15ml of BCOD solution (0.1%) were added. The mixture was then made up exactly to 50ml with water. (Alternatively, more than 1% for copper, 30ml of ethyl alcohol and 30ml of BCOD solution were added, and the solution was diluted exactly to 200ml with water.) An aliquot was transferred to an absorption cell (10 or 20mm), and the absorbance was measured at 610mμ against water.