Ion flotation and flame atomic absorption spectrophotometric determination of nickel and cobalt in environmental and pharmaceutical samples using a thiosemicarbazone derivative

Abstract

THIOPHENE-2-Carboxaldhyde-4-Phenyl thiosemicarbazone (TAPT), a NS containing ligand, combines with Ni (II) and Co (II) each individually and in combination, to form complexes in aqueous solution. These complexes could be successfully separated by a surfactant mediated methodology using oleic acid (HOL) surfactant. The concentration of the separated analytes was determined by flame atomic absorption spectrometry (FAAS). The different parameters affecting the flotation efficiency such as pH, the concentration of TAPT and surfactant, temperature and sample volume, were optimized. The interference from different cations and anions was studied. Beer’s law was obeyed over a concentration range of 0.5 - 4.0 ppm. The analytical detection limits were 2.5 and 2.8 ng/L for of Ni (II) and Co (II), respectively. The recoveries of Ni (II) and Co (II) from the synthetic mixtures and water samples are > 96 % and the relative standard deviations (RSD) were below 1.2%. The proposed method was successfully applied to the determination of nickel and cobalt in environmental water samples as well as the determination of cobalt in B12 vitamin samples. The mechanism of flotation is proposed.