Pyridylazonaphthols (PANs) and pyridylazophenols (PAPs) as analytical reagents. Part III. Formation of copper(II) complexes and their determination in alloys

Abstract

The reactions between copper(II) and 2-(2-pyridylazo)-1-naphthol (o-α-PAN) and 4-(2-pyridylazo)phenol (p-PAP) have been studied by spectrophotometry and graphical analysis, and their equilibrium constants have been determined. A rapid and simple method for the spectrophotometric determination of copper in aluminium alloys has been devised. A solution of the alloy with pH 2 is extracted with an equal volume of a 5 × 10^–3M solution of o-α-PAN in carbon tetrachloride and the absorbance of the extract is measured at 590 nm. The method has been checked by the analysis of standard alloys. The effect of interferences is discussed. The extraction behaviour of several cations with o-α-PAN is discussed and the sequential separation of copper(II), zinc(II), manganese(II) and lead(II) is outlined.