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 epsilon = 7.79 x 10(4) L mol(-1) cm(-1) at 510 nm and 2.21 x 10(4) L mol(-1) cm(-1), and their overall stability constants were K = 3.41 x 10(9) and 1.80 x 10(4) respectively. The precision of copper and silver determinations was 2.3% and 3.1%, respectively.