Fullerene: a Sensitive and Selective Sorbent for the Continuous Preconcentration and Atomic Absorption Determination of Cadmium

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Abstract
Ultratrace levels of cadmium were quantitatively sorbed on a C 60 fullerene mini-column to form neutral chelates, which were eluted with 200 µl of isobutyl methyl ketone and transferred to an atomic absorption spectrometer. Two chelating reagents, viz. , ammonium pyrrolidinedithiocarbamate (APDC) and 8-hydroxyquinoline, were tested in a simple flow system. The adsorption constant was dramatically increased for the APDC reagent and C 60 fullerene, and cadmium was selectively separated from co-existing copper, lead, zinc and iron, among other metals. Similar experiments were performed in parallel by using C 18 -bonded silica as sorbent. The concentration factor achieved was 110 and the detection limit was 0.3 ng ml -1 Cd. For analytical validation, cadmium was determined in certified reference biological samples; only the APDC method with C 60 fullerene as sorbent provided accurate results.