SAMPLING AND ANALYTICAL METHODS FOR THE DETERMINATION OF COPPER, CADMIUM, ZINC, AND NICKEL AT THE NANOGRAM PER LITER LEVEL IN SEA-WATER

Sea-water samples collected by a variety of clean sampling techniques yielded consistent results for copper, cadmium, zinc, and nickel, which implies that representative, uncontaminated samples were obtained. A dithiocarbamate extraction method coupled with atomic absorption spectrometry and electrothermal atomization is described which is essentially 100% quantitative for each of the four metals studied, has lower blanks and detection limits, and yields better precision than previously published techniques. A more precise and accurate determination of these metals in sea water at their natural ng l-1 concentration levels is therefore possible. Samples analyzed by this procedure and by concentration on Chelex-100 showed similar results for cadmium and zinc. Both copper and nickel appeared to be inefficiently removed from sea water by Chelex-100. Comparison of the organic extraction results with other pertinent investigations showed excellent agreement. © 1979.