Metal ligand complexes of alpha nitroso beta naphthol

Alpha nitroso beta naphthol is a well known gravimetric reagent and can also be used for extractive spectrophotometric determination of metal ions.1 The foremost advantages of the method are its high sensitivity and reproducibility but it suffers from sensitivity towards ammonia concentration and the low solubility of cobaltnitrosonaphtholate. Modification of the gravimetry methodology was carried out by Chatterjee et al.,2 wherein precipitation was carried out in acidic solution with a reagent prepared by heating alpha-nitrosobeta-naphthol in a mixture of glacial acetic acid, hydrogen peroxide and syrupy phosphoric acid. The complex of cobalt was ignited and weighed. There was no interferences from ions like iron(III), copper, chromium(III), vanadium(V), tungsten(VI), aluminium, molybdenum, nickel, titanium, zirconium, uranium(VI) and cerium.