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Abstract
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A novel magnetic solid phase extraction (MSPE) method applying a nanosorbent based on
Ni-Al layered double hydroxide/magnetite nano-hybrid (Ni-Al LDH/Fe3O4) was developed for
preconcentration and speciation of Mn(VII)/Mn(II) in aqueous solutions by flame atomic
absorption spectrometry. The synthesized Ni-Al LDH/Fe3O4 nano-hybrid was characterized by Xray
diffraction, Fourier transform infrared spectrometry, scanning electron microscopy and energy
dispersive X-ray spectroscopy. The prepared nano-sorbent can selectively extract Mn(VII) ions,
due to the negative charge of MnO4
‒ ions. The total Mn and thus indirectly Mn(II) were determined
after pre-oxidation of Mn(II) to Mn(VII) with acidic solution of potassium periodate. Various
parameters affecting the extraction recovery such as the amount of Ni-Al LDH/Fe3O4 nano-hybrid,
pH of the solution, extraction time, eluent conditions, sample volume and interfering ions were
investigated. Applying optimum conditions, the developed method was successfully used to the
speciation of Mn(VII)/Mn(II) species in various water samples with linear dynamic range of 0.4–
150 ng mL−1 (R2 = 0.9998) and detection limit of 0.1 ng mL−1. The method precision was evaluated
with six replicates at a concentration level (80 ng mL‒1), and a relative standard deviation of 3.3%
was obtained. The method was applied for determination of Mn(VII)/Mn(II) species in spiked real
water samples and the relative recoveries in the range of 93.6 to 103.3% were obtained.
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