Abstract
Preconcentration of Cd and Pb at ultratrace level in waters following filtration through silver nanoparticles-cellulose composites used for thin-film microextraction was performed. The new procedure was based on the formation of pyrrolidine dithiocarbamate (APDC) derivatives, which showed a large affinity toward the AgNPs. For this purpose, cellulose filters modified with AgNPs were prepared in situ upon reduction of silver ions by sodium tetrahydroborate. The effect of several experimental parameters such as the kind of derivatization agent and its concentration, sample pH, desorption conditions and volume of filtered sample was assessed. Cd and Pb were quantitated in the eluates by inductively coupled plasma-mass spectrometry (ICP-MS). Filters were characterized by scanning electron microscopy (SEM) in backscattering electron mode and combined with energy dispersive X-ray spectrometry, showing the presence of Ag and S in the cellulose filter. The repeatability expressed as relative standard deviation (RSD,%) was 1.4% for Cd and 5.8% for Pb. Methodological detection limits were 0.6 and 8.5 ng/L for Cd and Pb, respectively. The method was applied to several environmental waters.