Electrochemical masking of indium in a.c. polarographic determination of cadmium

Abstract A polarographic method for the determination of cadmium, without any previous separation of large amounts of indium is described. The anionic surfactant Benax serves as electrochemical masking agent for negatively charged metal citrate complexes but does not affect a.c. polarograms of uncomplexed cadmium ions. In citrate buffer at pH 3.5–4 with 0.03% Benax present, cadmium, can be determined in the presence of 10,000-fold amounts of indium. No other frequently associated metals interfere in the determination.