Selectively light scattering spectrometric detection of copper (II) based on a new synthesized oxamide ligand.

Light scattering (LS) signals have been applied for analytical detections, but the selectivity is poor. In order to improve the selectivity, pre-separation or new machines are generally considered. Differing from these methods, we synthesized a highly selective oxamide ligand, N',N'-bis (2-aminophenyl) oxamide (NAPO). It was found that the LS signals of NAPO, measured with a common spectrofluorometer, could be selectively enhanced by copper ion in neutral medium. Thus, a new highly selective detection method for copper ion could be developed over the range of 0.9-31.0 microM with the limit of determination of 97.6 nM (3sigma). Foreign ions including Cd(II), Al(III) could be allowed even if present at the level of 7-fold more than that of Cu(2+), avoiding pre-separation procedures from complicated samples such as real wastewater samples. Mechanism studies showed that the reaction between NAPO and copper ion could form some kinds of clusters and induce the enhanced LS signals.