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

An extractive spectrophotometric method is described for the determination of cobalt(II) using pyridine-2-acetaldehyde salicyloylhydrazone (PASH) as r eagent. For the extraction of cobalt(II) various experimental parameters su ch as acidity, reagent concentration, equilibration time are systematically studied to establish optimum conditions for quantitative extraction. Cobal t(II) is extracted quantitatively in the pH range 1.0 - 4.0. The yellow col oured 1:2 metal:ligand complex in chloroform is determined spectrophotometr ically at 415 nm. Beer's law was obeyed over the concentration range of 0.5 -7.0 mug mL(-1) of cobalt(II). The molar absorptivity and Sandell sensitivi ty were found to be 1.04 x 10(4) L mol(-1) cm(-1) and 5.63 ng cm respective ly. The method is precise and simple. It was applied for the analysis of hi gh speed steels and pharmaceutical samples for the estimation of cobalt(II) .