Determination of seven trace elements in natural waters after separation by solvent extraction and anion-exchange chromatography

A method is described for the determination of cadmium, cobalt, copper, manganese, lead, uranium, and zinc in samples of natural waters. After acidification with hydrochloric acid, the water sample is filtered and the diethyldithiocarbamates of the trace elements are isolated by extraction with acetone--chloroform (2:5) at pH 5. Following this preconcentration step, the metal ions are adsorbed on a column of the strongly basic anion-exchange resin Dowex 1-X8 (chloride form) using as sorption solution a mixture (5:4:1,v/v) of tetrahydrofuran, methyl glycol and 6 M hydrochloric acid. Successive elution is effected with 6 M hydrochloric acid (Co, Cu, Mn and Pb), 1 M hydrochloric acid (U) and 2 M nitric acid (Cd and Zn); the metal ions in the eluates are determined by atomic absorption spectrophotometry (except uranium, which is determined fluorimetrically). The procedure was used to determine the trace metals in water and snow samples collected in Austria and to analyse a sample of sea water from the Adriatic Sea