DIRECT DETERMINATION OF CADMIUM IN SEA-WATER USING ELECTROTHERMAL ATOMIZATION ATOMIC-ABSORPTION SPECTROMETRY WITH ZEEMAN-EFFECT BACKGROUND CORRECTION AND OXALIC-ACID AS A CHEMICAL MODIFIER

A method for the determination of cadmium in sea-water using an electrothermal atomization atomic absorption spectrometry system with Zeeman-effect background correction is presented. The effect of various inorganic and organic acids, used as chemical modifiers, on the atomization of cadmium and the sea-water background absorption signals were examined. Of all the different modifiers studied, oxalic acid suppresses chloride interference, promotes a lower atomization temperature and does not introduce any simultaneous significant background absorption signal, and was therefore of particular interest. Optimization of the experimental conditions gave a characteristic mass of 0.23 pg. For an injection of 99-mu-l of sea-water into the furnace, the detection limit was 3 ng l-1.