Spectrophotometric and spectrofluorimetric determination of the ternary complexes of cadmium(II) and zinc(II) with 2,2′-bipyridine and Rose Bengal Extra

Abstract

A sensitive and selective ternary complex system has been developed for the determination of cadmium(II) and zinc(II). This system consists of the metal ion, an organic base, 2,2′-bipyridine, and the fluorescein dye Rose Bengal Extra (RBE). The ternary complexes of both cadmium(II) and zinc(II) exhibit a sensitivity or molar absorptivity of 1.03 × 10⁵ and 9.97 × 10⁴ l mol^–1 cm^–1, respectively. Preliminary studies showed an enhancement of the secondary fluorescence spectra of the bipyridine-RBE complex system for cadmium(II) and zinc(II). This enhancement is the basis of the fluorimetric determination of cadmium(II) and zinc(II). This metal ion-bipyridine-RBE system has a linear fluorescence calibration range from 1.0 × 10^–6 to 14.0 × 10^–6M(0.06–0.91 p.p.m. Zn^II and 0.11–1.54 p.p.m. Cd^II).