Magnesium aluminate spinel nanoparticle-assisted dispersive solid-phase microextraction for cadmium determination in Camellia sinensis infusions by flame atomic absorption spectrometry.

Magnesium aluminate spinel nanoparticles (MgAl₂O₄-NP) were employed as the sorbent in a dispersive solid-phase microextraction coupled to flame atomic absorption spectrometry system (MgAl₂O₄-dSPME-FAAS) for the determination of cadmium. MgAl₂O₄-NP material was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy to confirm the spinel phase and particle morphology. Method performance was established from recovery experiments. The limit of detection was determined as 0.263 μg L-1. Relative to direct FAAS analysis, the enhancement in calibration sensitivity was found to be 105. Applicability to a plant-based matrix was examined in Camellia sinensis infusion (Ceylon tea) using matrix-matched spikes, and recoveries were obtained in the range of approximately 83% to 103%, indicating acceptable accuracy under realistic sample conditions. The workflow is operationally simple, and affords low detection limits together with reliable quantification, supporting the use of MgAl₂O₄-dSPME-FAAS for routine cadmium monitoring in aqueous media and tea infusions.