N-Nitroso-N-phenylhydroxylamin,Ammoniumsalz

VerwendenThe reagent used to be considered as specific for iron(II) and copper(II). However, in the course of later analytical studies it turned out that cupferron forms complexes with several other metals too, even in acidic medium. It is used today primarily for the determination of copper(II), but it has proved suitable for the determination of aluminium(III), bismuth(III), iron(III), mercury(II), thorium(IV), tin(IV), titanium(III), vanadium(IV) and zirconium(IV) as well. Of these, the zirconium(IV) complex is the most stable. Cupferron precipitates zirconium(IV) quantitatively from aqueous media containing sulfuric acid. The reagent gives a precipitate with most of the above metal ions even in strong mineral acidic medium. Only the aluminium(III) complex does not precipitate in the presence of mineral acids. By means of cupferron many metal ions can be separated: thus, for instance, iron(III) can be separated from aluminium(III) and manganese(II) and titanium (IV), zirconium(IV) and hafnium(IV) from many other metal ions, etc. Though the reagent makes possible several separations, the precipitates are not exactly of stoichiometric composition (they almost always contain some excess of the ligand). Hence instead of being directly weighed, the precipitates are usually ignited and the metal oxide residues weighed.