DIRECT GRAPHITE-FURNACE ATOMIC-ABSORPTION SPECTROMETRIC DETERMINATIONOF METALS IN SEA-WATER - APPLICATION OF PALLADIUM MODIFIERS AND A FRACTAL APPROACH TO THEIR ANALYTICAL SUPPORT

Sea water, like other high-salinity matrices, causes severe interferen ces in the direct determination of metals by graphite furnace atomic a bsorption spectrometry (GFAAS), even when Zeeman-effect background cor rection is applied. A method for eliminating these interferences by th e application of mixed modifier system of ammonium oxalate and tetraam minepalladium(II) chloride is presented. In particular these modifiers optimize the direct GFAAS determination of lead and manganese. For ca dmium, however, only ammonium oxalate should be used as a modifier. Th e geometry of the microdistribution of palladium on the palladium-cond itioned graphite platform was investigated in order to elucidate possi ble stabilizing effects of palladium on the analytes which were observ ed with the different modifiers. Fractal characteristics of the pallad ium elemental distribution were ascertained by a scanning electron mic roscope-energy-dispersive x-ray spectrometer image box-counting analys is. The fractal dimension [D(B)(0) = 1,77 +/- 0.04 and 1.81 +/- 0.04] and electron microscopic investigations indicated differences in the s tructure of palladium deposits on the platform. These variations in th e palladium geometry affect the analytes to a certain extent.