FLAME ATOMIC-ABSORPTION SPECTROMETRIC DETERMINATION OF CADMIUM IN BIOLOGICAL SAMPLES USING A PRECONCENTRATION FLOW SYSTEM WITH AN ACTIVATEDCARBON COLUMN AND DITHIZONE AS A CHELATING AGENT

A combined flow atomic absorption spectrometric system was used to dev elop an efficient on-line preconcentration-solvent elution procedure f or the determination of trace amounts of cadmium. The metal was precon centrated as the dithizonate on a mini-column packed with activated ca rbon and eluted with isobutyl methyl ketone (4-methylpentan-2-one) int o the nebulizer. A preconcentration factor of 40-130, equivalent to 3- 12 ml of sample, was achieved by using a time-based technique. The det ection limit obtained (3sigma) ranged between 0.3 and 1.3 ng ml-1 and the relative standard deviation from 1.3 to 2.4% for a sample volume o f 12 and 3 ml, respectively. The results obtained for the determinatio n of cadmium in reference materials testify to the applicability of th e proposed procedure to the analysis of biological materials.