Flame atomic absorption spectrometric determination of copper, lead, and cadmium in Gastrodiae rhizoma samples after preconcentration using magnetic solid-phase extraction

In this research, ferroferric oxide nanoparticles were coated with silicon dioxide and further functionalized with alizarin complexone as the adsorbent of magnetic solid-phase extraction, thus aiming for extraction and preconcentration of heavy metals in Gastrodiae rhizoma samples. The determination of heavy metals was carried out by flame atomic absorption spectrometry. The results showed that the functionalized magnetic nanoparticles demonstrated higher extraction efficiency for copper, lead, and cadmium. The synthesized magnetic sorbents were characterized by transmission electron microscope, X-ray diffraction, and Fourier-transformed infrared spectra. Different parameters influencing the extraction efficiency including the amount of sorbent, sample pH, sorption time, solution volume, elution solvent, and reuse times were optimized. Under the optimal conditions, the method detection limit was 0.18, 0.25, and 0.12 µg/L for copper, lead, and cadmium, respectively. The proposed method was successfully applied to extract copper, lead, and cadmium in Gastrodiae rhizoma samples, and the recoveries of the samples ranged from 90.0 to 102.0% and relative standard deviations (n = 5) were in the range of 1.93–3.82%.