Spectrophotometric determination of copper in alloys and pharmaceutical preparations

A sensitive spectrophotometric method for the determination of trace amounts of copper is described. The method is based on the determination of the ligand thenoyltrifluoroacetone (TTA) associated with copper(II)-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 is coupled with diazonium chloride generated by the reaction of para-nitroaniline with sodium nitrite to form an azo dye with an absorption maximum 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 has been applied to the determination of copper in alloys and pharmaceutical samples.