Nickel oxide/chitosan nano-composite as a magnetic adsorbent for preconcentration of Zn(II) ions

In this work, a magnetic nickel oxide/chitosan nanocomposite was fabricated by a facile precipitation approach. The structure and morphological properties of the prepared nano-material were characterized via X-ray diffraction, Fourier transform infrared spectrometry, scanning electron microscopy and energy dispersive X-ray spectroscopy. The prepared nanocomposite was used as a nano-sorbent for the magnetic solid-phase extraction (MSPE) of the trace amounts of zinc (Zn(II)) ions from aqueous solutions followed by flame atomic absorption spectrometric (FAAS) detection. Several factors influencing the extraction efficiency of Zn(II) ions such as pH, extraction time, amount of the nano-sorbent, elution conditions and sample volume were investigated and optimized. Under optimized conditions, the calibration curve with a liner dynamic range of 0.35-15 ng mL(-1) was attained. The preconcentration factor and limit of detection were 100 and 0.12 ng mL(-1), respectively. The method precision was evaluated with seven replicates at the concentration level of 5 ng mL(-1) and the relative standard deviations of 2.8% and 3.1% were obtained for infra-day and inter-day repeatability, respectively. The applicability of the developed MSPE-FAAS method for the measurement of Zn(II) ions was validated by analyzing the certified reference material NIST SRM 1549. Zinc(II) ion concentration was measured in various real samples including tap water, river water, well water, milk and powder milk using the method, and satisfactory relative recovery values were acquired for the spiked samples.