Spectrophotometric determination of cobalt after separation by adsorption of its ternary complex with 4′-(p-methoxyphenyl)-2,2′ :6′,2″-terpyridine and tetraphenylborate on to microcrystalline naphthalene

Abstract

A spectrophotometric method for the determination of cobalt after adsorption of its ternary complex with 4′-(p-methoxyphenyl)-2,2′:6′,2″-terpyridine (MPTP) and tetraphenylborate (TPB) on to microcrystalline naphthalene has been developed. The insoluble cobalt ternary complex formed at pH 4.0–11.1 has an absorption maximum at 518 nm and a molar absorptivity of 3.3 × 10³ l mol^–1 cm^–1. The complex is quantitatively adsorbed on to microcrystalline naphthalene by vigorous shaking for a few seconds and is stable in acetonitrile for more than 6 d. Simple and direct spectrophotometric methods are described for the determination of cobalt in reference materials and practical samples.