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

Cobalt(ll) and gold(lll) react with 2,4-dihydroxy acetophenone oxime (RPO) formi ng yellowish brown and greyish green coloured soluble complexes respectively. The reactions are very slow but become fast in the presence of K2SPxThis may be due to the enhancement of aerial oxidation of metal complexes wi th RPO in their lower oxidation states (Co(! I), Au( III )) to coloured complexes with higher oxidation state (Co(lll ), Au(Y)). The Co(III )-RPO complex shows A.na, at 390 nm and at pH 9.5 obeying Beer 's law in the range 0.121.80 )lg/ml. Determination of Au (lll ) is carried out at 630 nm and pH 3.5 where Beer 's law is obeyed in the range of 0.39-5.12 )lg/ ml of Au(! II) . The effect of forei gn ions in the method is studied. The method is applied for the analysis of Co( II ) in vitamin B 12 and Au(lll)