Determination of micro amount of Cobalt (II) by Using Antipyriyl azo pyrogallol

Abstract

A new , simple , sensitive and rapid spectrophotometric method is proposed for the determination of trace amount of cobalt (II) . The method is based on the formation of a 1:1 complex with  4-(4^′- pyrazolon azo) pyrogallol (APAP) as a new reagent is developed . The complex has a maximum absorption at 463  nm and ε_max of  1.8 X 10⁴  L. mol^-1. cm^-1 . A linear correlation (0.05 – 1.5 μg. ml^-1) was found between absorbance at λ_max and concentration . The accuracy and reproducibility of the determination method for various known amounts of cobalt (II) were tested . The results obtained are both precise (RSD was better than 1.45 % ) and accurate (relative error was better than  0.6 %   ) . The effect of diverse ions on the determination of cobalt (II) to investigate the selectivity of the method were also studied . The stability constant of the product was 5.71 X 10⁴  L. mol^-1 . The proposed method was successfully applied to the analysis of dust and synthetic mixtures without any preliminary concentration or separation.