PALLADIUM AS A CHEMICAL MODIFIER FOR THE DETERMINATION OF MERCURY IN MARINE SEDIMENT SLURRIES BY ELECTROTHERMAL ATOMIZATION ATOMIC-ABSORPTION SPECTROMETRY

A method for the determination of mercury in marine sediment slurries by electrothermal atomization atomic absorption spectrometry was optimized. It was found that a particle size < 20 mu m is sufficient to achieve total atomization of the mercury content in the solid particles of the slurry. This particle size was achieved with simple mechanical grinding, using zirconia beads. The use of different thickening agents, viz., Triton X-100, Viscalex HV30 and glycerol, during the slurry preparation was studied. In addition, an acid predigestion was applied to verify the efficiency of the slurry sampling. The use of palladium at a concentration of 15 mg 1(-1) was found satisfactory for stabilizing mercury at 200 degrees C. Three charring steps, two involving an oxidative process, were studied. The optimum atomization temperature was 1450 degrees C. A limit of detection of 70 mu g kg(-1) was achieved. The standard additions method was used for the determination of mercury in marine sediment samples from the Galician coast, the levels being between 2.2 and 3.2 mg kg(-1).