Sensitive colorimetric determination of copper (II) ions in some chemicals and multivitamins

A sensitive and selective colorimetric method has been devised for the micro-determination of copper (II) ions in pure form, some chemicals and multivitamin preparations. The method depends on the formation of stable blue complexes in ammonia medium peaking at 615 nm between copper (II) ions, oxalyldihydrazide and one of the following aldehydes: 4-nitrobenzaldehyde, 2-nitrocinnamaldehyde and formaldehyde with minimum detection limits 0.1, 0.16 and 1.1 ppm, respectively. Several metal ions do not interfere. The optimum reaction conditions were studied and the results obtained were favorably comparable to the diethyldithiocarbamate method.