Preconcentration of Pb(II) by using Mg(II)-doped NiFe2O4 nanoparticles as a magnetic solid phase extraction agent.

Magnesium(II)-doped nickel ferrite (Mg-NiFe2O4) nanoparticles are introduced as a new adsorbent for magnetic solid phase extraction of lead(II) ions from aqueous solutions. The structure and morphology of the adsorbent was characterized by FTIR, X-ray diffraction and scanning electron microscopy. The effects of pH value, amount of adsorbent, type, concentration and volume of the eluent and adsorption/desorption time on the extraction efficiency were studied. Following elution with hydrochloric acid, Pb(II) ions were quantified by flame atomic absorption spectrometry. Under optimized conditions, the calibration graph is linear in the 0.5-125 ng mL-1 Pb(II) ion concentration range. Other figures of merit include (a) a 0.2 ng mL-1 limit of detection, (b) an enrichment factor of 200, (c) an intra-day relative standard deviation (for n = 6 at 50 ng mL-1) of 1.6%, and (d) an inter-day precision of 3.8%. The method was validated by the analysis of the certified reference material, NIST SRM 1566b. It was successfully applied to the determination of Pb(II) ion in spiked water samples, industrial wastewater and acidic lead battery waters. Graphical abstract Schematic of the synthesis of Mg(II)-doped NiFeO4 nanoparticles and their application as a magnetic sorbent for solid-phase extraction of a Pb(II) ions prior to determination by flame atomic absorption spectrometry (FAAS).