Pyridine-2-acetaldehyde salicyloylhydrazone as reagent for extractive and spectrophotometric determination of cobalt(II) at trace level

Abstract

An extractive spectrophotometric method is described for the determination of cobalt(II) using pyridine-2-acetaldehyde salicyloylhydrazone (PASH) as reagent. For the extraction of cobalt(II) various experimental parameters such as acidity, reagent concentration, equilibration time are systematically studied to establish optimum conditions for quantitative extraction. Cobalt(II) is extracted quantitatively in the <i>p</i>H range 1.0-4.0. The yellow coloured 1:2 metal:ligand complex in chloroform is determined spectrophotometrically at 415 nm. Beer's law was obeyed over the concentration range of 0.5-7.0 μg mL^-1 of cobalt(II). The molar absorptivity and Sandell sensitivity were found to be 1.04×10⁴ L mol^-1 cm^-1 and 5.63 ng cm^-2 respectively. The method is precise and simple. It was applied for the analysis of high speed steels and pharmaceutical samples for the estimation of cobalt(II).