SALICYLAMIDOXIME AS AN ANALYTICAL REAGENT. PART II. GRAVIMETRIC ESTIMATION OF COPPER AND NICKEL AND THEIR SEPARATION FROM OTHER METALS

The use of salicylamidoxime as a reagent for the gravimetric estimation of copper and nickel by weighing the precipitates of composition M(C7H7O2N2)2, where M=Cu or Ni, after drying at 110o, is described. Copper can he effectively separated from mercuryII , lead, cadmium, zinc, manganeseII and cobaltII by precipitating the copper with an excess of the amidoxime at a PH of 4.0-4.5; while for the separation from ironIII, antimonyIII and bismuthIII, the precipitation should be carried out in presence of sufficient tartaric acid at PH of 4.0-4.5. Nickel can similarly be separated from zinc quantitatively by precipitation with the reagent at a controlled PH (7.0-7 5) in the presence of some ammonium chloride to prevent the precipitation of the latter element. Determinations of copper and nickel in mixed solutions have been carried out by precipitating copper in an acetate-buffer of PH near about 4; in the filtrates nickel was precipitated by adding more of the reagent and then ammonia to adjust the PH of the solution to 7.0-7.5