PALLADIUM NITRATE MAGNESIUM-NITRATE MODIFIER FOR ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROMETRY .3. DETERMINATION OF MERCURY IN ENVIRONMENTAL STANDARD REFERENCE MATERIALS

A single addition of 15-mu-g of palladium is sufficient for 40-60 determinations of mercury if the graphite tube is not heated to temperatures higher than 1500-degrees-C in the cleaning step. A pyrolysis temperature of 400-degrees-C can be used without any loss of mercury, and a characteristic mass of 0.1 ng of mercury was obtained for an atomization temperature of 1000-degrees-C. Interferences caused by high sodium chloride concentrations could be eliminated by using a mixture of 95% argon and 5% hydrogen as the purge gas. Mercury could be determined accurately in Aquatic Plant, Albacore Tuna, River Sediment and Coal Fly Ash reference materials.