BIGUANIDE SULPHATE AS A REAGENT FOR THE ESTIMATION OF COPPER.

Copper biguanide sulphate, which forms a very sparingly soluble inner-metallic complex salt of the second order, has been utilised for the estimation of copper. Zinc, cadmium, molybdenum (Mo6+), tungsten (Wo6+), magnesium and alkali metals do not interfere with the estimation. The solution must not contain any nitrate. as the corresponding copper biguanide nitrate is also sparingly soluble. The precipitate, dried at 50°-70°, has the composition [Cu (C2N5H7)2]SO4.3H2O, and is weighed as such. The estimation can be made on both macro and semi-micro scale with very good results. using only a good quality macro analytical balance In the absence of a large excess of ammonium salt and ammonia the method has also been employed for the volumetric estimation of copper with rubeanic acid as an external indicator