Spectrophotometric investigation of trace copper and silver complexes with a new chromogenic ligand,o-methylbenzenediazoaminobenzene-p-azobenzene

The synthesis of o-methylbenzenediazoaminobenzene-p-azobenzene (o-MDAP) was made. At pH 12, copper and silver formed a sensitive complex with o-MDAP. The characteristics of copper and silver complexes have been determined. The results showed that the formed complexes were Cu(o-MDAP)2 and Ag(o-MDAP), respectively. Their true molar absorptivities were equal to ε = 7.79 x 10⁴ L mol^-1 cm^-1 at 510 nm and 2.21 x 10⁴ L mol^-1 cm^-1, and their overall stability constants were K = 3.41 x 10⁹ and 1.80 x 10⁴ respectively. The precision of copper and silver determinations was 2.3% and 3.1%, respectively.