Sodium bis (2-hydroxyethyi) dithlocarbamate (NaHEDC) is used to form neutral metal complexes with metals of the hydrogen sutfMe group. The hydroxy groups present in NaHEDC cause the metal complexes to be watgr-soluble at low concentrations. The compiexed metal Ions can be separated into groups or concentrated from very dilute solution by sorption on a small column of XAD-4 resin. Selectivity is achieved by pH ...