Spectrophotometric determination of cobalt(II) and gold(III) in the presence of potassium persulphate using resacetophenone oxime

Abstract

Cobalt(II) and gold (III) react with 2,4-dihydroxy acetophenone oxime (RPO) forming yellowish brown and greyish green coloured soluble complexes respectively. The reactions are very slow but become fast in the presence of K₂S₂O₈. This may be due to the enhancement of aerial oxidation of metal complexes with RPO in their lower oxidation states (Co(II), Au( III)) to coloured complexes with higher oxidation state (Co(III), Au(V)). The Co(III)-RPO complex shows λ_maxat 390 nm and at <i>p</i>H 9.5 obeying Beer's law in the range

0.12-1.80 μg/ml. Determination of Au(III) is carried out at 630 nm and <i>p</i>H 3.5 where Beer's law is obeyed in the range of 0.39-5.12μg/ml of Au(III). The effect of foreign ions in the method is studied. The method is applied for the analysis of Co(II) in vitamin B₁₂ and Au(III) in Rheumartho Pharmaceutical sample.