Magnetic Solid Phase Extraction of Lead (II) and Cadmium (II) From Water Samples Using ZnO@Fe3O4 Nanoparticles Combined With Flame Atomic Absorption Spectrometry Determination

A new magnetic solid phase extraction method was developed utilizing magnetically enhanced zinc oxide (ZnO@Fe₃O₄) nanoparticles for the separation and enrichment of lead (II) and cadmium (II) before sample determination through flame atomic absorption spectrometry. The ZnO@Fe₃O₄ nanoparticles synthesized by the hydrothermal method were characterized by x-ray diffraction, scanning electron microscopy, and energy-dispersive x-ray spectroscopy. The experimental factors like pH (6.0), eluent type and concentration (1 M nitric acid for lead (II), 1 M hydrochloric acid for cadmium (II)), adsorbent amount (150 mg for lead (II), and 200 mg for cadmium (II)), sample volume (5 mL), and extraction time (5 min for lead (II), and 10 min for cadmium (II)) were optimized. Under the optimization conditions, limits of detection of 2.36 and 7.86 µg/L for lead (II) and cadmium (II) were obtained with a wide concentration range from 50 to 5000 µg/L, respectively. The presented method was successfully applied to real water samples with spiked recoveries in the range of 99.2%–101% for lead (II) and 99.6%–100% for cadmium (II).