Preconcentration of trace amounts of lead in water samples with cetyltrimethylammonium bromide coated magnetite nanoparticles and its determination by flame atomic absorption spectrometry

A sensitive and simple magnetic solid phase extraction procedure was presented for the preconcentration of lead ions in environmental water samples. In the present study, lead ions form complexes with 1-(2-pyridilazo)-2-naphthol reagent (PAN) in basic medium, and then are quantitatively extracted to the surface of cetyltrimethylammonium bromide (CTAB)-coated magnetite nanoparticles (Fe3O4 NPs). After magnetic separation of adsorbent, the adsorbent was eluted with 0.5% (v/v) HCl in methanol prior to its analysis by flame atomic absorption spectrometry (FAAS). The pH of sample, concentrations of PAN, amounts of CTAB and Fe3O4 NPs, sample volume and desorption conditions were optimized. Under optimum conditions, the calibration curve was linear in the range of 0.05-100 ng mL−1 with R2 = 0.9996. Detection and quantification limits of the proposed method were 0.005 and 0.05 ng mL−1, respectively. Enhancement factor of 1050 was achieved using this method to extract 1000 mL of different environmental water samples. Compared with conventional solid phase extraction methods, the advantages of this method still include easy preparation of sorbents, short times of sample pre-treatment, high extraction yield, and high breakthrough volume. It shows great analytical potential in preconcentration of lead from large volume water samples.