Determination of Cadmium and Lead in Tap Water by Graphite-Furnace Atomic Absorption Spectrometry after Preconcentration on a Finely Divided Ion-Exchange Resin as the Pyrrolidinedithiocarbamate Complexes

Abstract

A rapid and simple preconcentration method based on the combined use of ammonium pyrrolidinedithiocarbamate (APDC) and a finely divided anion-exchange resin has been described for the determination of trace amounts of cadmium and lead by graphite-furnace atomic absorption spectrometry (GFAAS). Cadmium- and lead-APDC complexes were extracted simultaneously on the resin at pH 6. The resin particles holding the cadmium- and lead-APDC complexes were separated by filtration and dispersed in 1.0 ml of 0.1 mol 1 -1 hydrochloric acid containing 100 μg of palladium(II). The resulting suspension was introduced directly into the graphite furnace by an automatic sampler. The detection limits of cadmium and lead in a 150-ml sample aliquot were 0.17 and 5.7 ng 1 -1 , respectively, based on three-times the standard deviation of blank values. The proposed method was applied to the determination of nanograms per liter levels of cadmium and lead in tap water.