Ultrasensitive fluorometric determination of aluminum using the CoFe2O4 NPs/SDS/oxine system with the aid of ultrasound waves†

In this study, we present a thoughtful integration of a dispersive solid-phase sorbent and oxine for the ultrasensitive and highly selective determination of Al³⁺ ions. Cobalt ferrite nanoparticles (CoFe₂O₄ NPs) modified with oxine were employed to facilitate the pre-concentration and estimation of Al³⁺, forming highly fluorescent chelate. The modification process included the assistance of sodium dodecyl sulfate (SDS) and sonication. The results indicated that the fluorescence intensity of Al³⁺-oxine/SDS@CoFe₂O₄ NPs surpassed that of Al³⁺-oxine alone. The confirmation of the successful functionalization of CoFe₂O₄ NPs with oxine was established through various techniques. Under optimal conditions, the fluorescence intensity exhibited a positive correlation with increasing concentrations of Al³⁺ within the range of 0.029–600 ng mL⁻¹, achieving a detection limit of 0.0087 ng mL⁻¹ based on signal to noise ratio 3 : 1. The developed method was effectively applied to the determination of Al³⁺ in drinking water samples, yielding recoveries in the range of 97.19% to 103.13%, with a relative standard deviation (RSD%) not exceeding 3.78%.