Zirconium materials are important and high purity is required in many fields of technology. The maximum allowable impurity concentration in nuclear grade zirconium is <100 μg/g for most elements, but <0.4 μg/g of cadmium is essential owing to its large neutron capture cross section. Cadmium in zirconium has been determined routinely by numerous techniques including emission spectroscopy. Dithizone-methylisobutylketone (MIBK), dithizone-chloroform, and sodium diethyl dithiocarbamate-chloroform were used to separate and concentrate cadmium in high-purity zirconium. Solvent extraction with ammonium pyrrolidine dithiocarbamate (APDC) is widely used for a variety of materials, because it allows a multi-element analysis of a single extract over a wide pH range. Back extraction from APDC-MIBK is seldom applied.
Lu Shang Jing and Ramon M. Barnes, "Determination of Cadmium in Pure Zirconium by Inductively Coupled Plasma-Atomic Emission Spectroscopy," Appl. Spectrosc. 38, 284-285 (1984)