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Abstract
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In this work, nickel ferrite magnetic nanoparticles were synthesized using a facile hydrothermal method. The
surface modification of the prepared nanoparticles was carried out using cross-linked starch as a good stabilizer
and biopolymer. The as-prepared nickel ferrite-starch nano-bio composite was characterized using numerous
techniques, and introduced as a novel adsorbent. The initial experimental results indicated that the adsorbent has
a good capability to extract lead ions (Pb(II)) from aqueous solutions. Hence, the adsorbent was applied for
dispersive magnetic solid-phase extraction of Pb(II) before flame atomic absorption spectrometric detection.
Some variables affecting the extraction efficiency such as sample volume (250.0 mL), pH (6.5), type and eluent
concentration (0.3 mol L–1 nitric acid), amount of the adsorbent (200 mg), extraction time (15 min), and
desorption time (15 min) were investigated and optimized. Moreover, the adsorption capacity (35.50 mg g–1),
stability and reusability (80 extraction/desorption cycles), and selectivity of the adsorbent towards the analyte
were studied. In the optimized conditions, the linear dynamic range of the constructed calibration graph is
between 0.5 and 140.0 ng mL–1. The limit of detection and limit of quantification of the method are 0.12 and
0.40 ng mL–1, respectively. The average intra-day and inter-day relative standard deviations (for n=6 and 5.0,
50.0 and 100.0 ng mL–1 Pb(II) concentration) are 2.02 % and 3.72 %, respectively. To validate the method, the
certified reference material NIST SRM 1643e was analyzed, and the method was used for the pre-concentration
and determination of lead ions in different sections of Moringa oleifera medicinal plant and several water samples.
The acceptable relative recovery values between 98.0 % and 102.7 % were attained for the spiked samples,
approving the ignorable matrix effect of the method.
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