Evaluation of bathocuproine for the spectro-photometric determination of copper(I) in copper redox studies with applications in studies of natural waters

Copper(I) is determined at submicromolar levels in the presence of copper(II) in aqueous media by spectrophotometric measurement of the copper(I) complex of bathocuproine (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline). Copper(II) interference produced by reduction to copper(I) is described. Ethylenediamine can serve as a masking ligand to inhibit Cu(II) interference. The limit of detection is 1 × 10−8 mol l−1. Although this is not sensitive enough for use at natural copper concentrations, the procedure can be used in laboratory studies of copper redox processes at elevated levels in natural waters such as sea water. The dependence of results on pH and ionic strength was studied to evaluate the usefulness of the method in other aqueous systems.