Magnetic dispersive solid phase extraction for simultaneous enrichment of cadmium and lead in environmental water samples

Abstract

A new magnetic dispersive solid phase extraction (MDSPE) method and graphite furnace atomic absorption spectrometry (GFAAS) have been combined for the simultaneous enrichment of Cd and Pb from environmental water samples including seawater, and subsequent sequential determination of both analytes. For the preconcentration, a shell structured Fe3O4@graphene oxide nanospheres was synthetized and characterized. This nanosorbent presents a large contact area and has a high surface density of polar groups. With the optimized method, the experimental detection and determination limits, calculated as the concentration of analyte giving signals equivalent to three and ten times, respectively, the standard deviation of the blank plus the net blank intensity, were 0.005 µg L-1 (detection limit) and 0.017 µg L-1 (determination limit) for Cd; and 0.008 µg L-1 (detection limit) and 0.026 µg L-1 (determination limit) for Pb. The method offers good precisions (RSD < 3.5%) and a preconcentration factor of 200. The accuracy of the proposed method was verified using certified reference materials (SLRS-5, SPS-SW2) and by determining the analytes content in spiked seawater and tap water samples collected from Málaga (Spain). The determined values by external calibration were in good agreement with the certified values and the recoveries for the spiked samples were around 100% in all cases.