Solutions of cyanide metal complexes were prepared by dissolv-ing the corresponding salts (K4Fe(CN)6, K3Fe(CN)6or K3Co(CN)6) or adding metal amounts (Cu2+, Cd2+, Ag+, Zn2+, Ni2+or Hg2+)to a cyanide solution taking into account the metal:cyanide stoi chiometric ratio (1:2, 1:3 or 1:4).
The cyanide concentration was equivalent to 50 g L−1 as CN− in all solutions.