Application of Co3O4 nanoparticles as an efficient nano-sorbent for solid-phase extraction of zinc(II) ions

In this research, a solid-phase extraction (SPE) method based on application of cobalt oxide nanoparticles (Co3O4 NPs) as a novel nano-sorbent was developed for preconcentration and extraction of zinc(II) ions from various real samples followed by flame atomic absorption spectrometric (FAAS) detection. Co3O4 NPs were simply synthesized via a thermal treatment of cobalt hydroxide after a precipitation method, and its structure and morphological properties were studied by Fourier transform infrared spectrometry, X-ray diffraction, and scanning electron microscopy. The effect of various parameters influencing the extraction recovery of Zn(II) ion such as extraction time, pH, amount of the nano-sorbent, sample volume and elution conditions were studied and optimized. Applying optimum conditions for SPE procedure, the limit of detection was 0.25 ng mL(-1) and the calibration graph was linear in the concentration range of 0.4-32 ng mL(-1 )with a correlation coefficient of 0.9951. The method intra- and inter-day precisions, calculated by performing five replicates at the concentration level of 20 ng mL(-1) were obtained 2.3% and 2.6%, respectively. The applicability of the developed SPE-FAAS method was evaluated by its application for measuring zinc concentration in various samples including tap water, river water, well water, milk and powder milk samples, and the relative recoveries were obtained in the range of 94.5-103.5% for the spiked samples.