Abstract
The authors planned out a new method for the polarographic determination of zinc after dithizone extraction. After the sample is decomposed by perchloric acid, citric acid is added to mask the interfering iron etc.. Ammoniac water is added up to pH 8.2. Zinc is extracted together with copper, nickel, etc. by dithizone-chloroform solution, and separated from iron. From the extract, zinc and lead is stripped with 0.1N hydrochloric acid.
The polarogram of zinc-ammin was made out using NH3+NH4Cl as supporting electrolyte. The behavior of zinc during the extraction process was studied on a synthetic sample which was made by adding independently twelve kinds of elements generally contained in steel. The determination was not disturbed by lead, copper and nickel accompanied, since their half wave potentials were different.
Where the cobalt content exceeded 0.3% zinc value was read a little higher as a bit of extraction of cobalt was observed in the process of the stripping by hydrochloric acid.
