Aluminum(III)-doped ZnO@Fe3O4 nanocomposite as a magnetic sorbent for preconcentration of cadmium(II)

An Al-doped ZnO@Fe3O4 nanocomposite was synthesized and used as a magnetic sorbent for solid-phase extraction of Cd(II) prior to its determination by flame atomic absorption spectrometry (FAAS). The size and morphology of the nano-sorbent were characterized via X-ray diffraction analysis, scanning electron microscopy and FTIR. Following its desorption with acetic acid, cadmium was quantified by FAAS. Factors affecting the extraction of the Cd(II) were optimized. Under optimized experimental conditions, the calibration graph is linear in the 0.6 to 60 ng mL(-1) concentration range. The limit of detection is 0.17 ng mL(-1) and the pre-concentration factor is 50. The inter- and intra-day relative standard deviations for six replicate determinations at a Cd(II) level of 40 ng mL(-1) are 3.8% and 2.5%, respectively. The method was successfully applied to the trace determination of Cd(II) in spiked water samples. The accuracy of the method was confirmed by analyzing the certified reference material NIST SRM 1643e.