A potentiometric method for the determination of nickel in gold and silver electroplating baths is described. The titration is carried out with KCN. Gold and silver are removed before titration by a reduction process. It is also possible to determine nickel in steel alloys, etc. (see the literature reference).
Ni2+ + 4 KCN + 2NH4+ → (NH4)2[Ni(CN)4] + 4 K+