SPECTROPHOTOMETRIC DETERMINATION OF COPPER IN ALLOYS AND PHARMACEUTICAL PREPARATIONS

A sensitive spectrophotometric method for the determination of trace a mounts of copper is described. The method is based on the determinatio n of the ligand thenoyltrifluoroacetone (TTA) associated with copper(I I)-TTA complex, which is formed at a pH of 7.50. The insoluble complex is collected over lead sulphate. The complex along with lead sulphate is solubilised using sodium acetate at pH of 5.50. The released TTA i s coupled with diazonium chloride generated by the reaction of para-ni troaniline with sodium nitrite to form an azo dye with an absorption m aximum at 535 nm in aqueous medium. The colour system obeys Beer's law cover the 0-8 mu g range of copper. The coefficient of variation is 2 .1% for ten determinations at the 6 mu g level. The proposed method ha s been applied to the determination of copper in alloys and pharmaceut ical samples.