Nickel–zinc ferrite (Ni0.5Zn0.5Fe2O4) nanosorbent was prepared and used for the efficient simultaneous preconcentration of arsenite and arsenate ions from aqueous solutions. The prepared nanoparticles were characterized by XRD measurements which indicated that the Ni0.5Zn0.5Fe2O4 nanoparticles were synthesized well. The SEM results showed an average diameter of 27 nm for the nanoparticles. The adsorption capacity was found to be 35.8 and 62.5 mg g−1 for As(III) and As(V), respectively. The adsorbed ions were then quantitatively eluted using 2 mL of 2 M NaOH solution as an elution solvent and determined spectrophotometrically. The maximum preconcentration factor for both the investigated ions was found to be 100. As(III) and As(V) species were determined in the mixture based on the difference in their adsorption behavior at different pHs. For an initial sample volume of 200.0 mL, the calibration graph was linear in the range 0.3–50.0 ng mL−1 of As(III) and 0.2–75.0 ng mL−1 of As(V) concentration. The method resulted in a successful determination of As(III) and As(V) in water samples.
