A Rapid and Sensitive Method for the Determination of Cobalt in Pharmaceutical and Ink Dryer Samples

Abstract

A simple extractive spectrophotometric method is reported for the determination of cobalt in pharmaceutical samples like vitamin B12 and in ink dryer. Picolinaldehyde nicotinoylhydrazone (PANH) has been used for the estimation of cobalt. The reagent forms a yellow colour complex with cobalt in the pH range 8.5-10.5, with absorption maxima at 370 nm. The complex is extractable into chloroform and obeys the Beer's law in the range 0.05- 2.7 μg mL^-1 of cobalt concentration. The molar absorptivity and the Sandell's sensitivity for cobalt (III)-PANH complex in chloroform has been found to be 4.014 x 104 L mol-1

cm-1 and 1.46 ng cm-2, respectively. Results are comparable with those obtained by AAS and certified values. The developed method is facile and economical.