Solid-phase Extraction on Magnetic Multi-walled Carbon Nanotubes Coupled with Flame Atomic Absorption Spectrometry for Determining Lead and Cadmium in Traditional Chinese Medicine

Summary: In this study, magnetic carbon nanotubes (MCNTs) were prepared by mixing the magnetic particles and multi-walled carbon nanotubes in dispersed solutions. These MCNTs were used as adsorbents of magnetic solid-phase extraction (MSPE). By coupling MSPE with flame atomic absorption spectrometry, a rapid and sensitive method for analyzing lead and cadmium using ammonium pyrrolidine dithiocarbamate as chelating reagent was established. Under optimal conditions, calibration graphs were linear in the range of 10.0–400.0 μg L -1 and 10.0–300.0 μg L -1 with detection limit of 0.6 μg L -1 and 0.5 μg L -1 for Pb and Cd, respectively. A good relative standard deviation for determining 300.0 μg L -1 of Pb and Cd were 3.8 and 3.4%, respectively. The proposed method was applied to analyze several traditional Chinese medicine samples with satisfactory results.