Simultaneous determination of lead and copper in Polygonatum kingianum by ICP OES combined with natural deep eutectic solvent-based magnetic dispersive micro solid phase extraction

Abstract

In this work, a natural deep eutectic solvent (NADES) was first used to modify a magnetic TiO₂ composite for magnetic dispersive micro solid phase extraction (MDMSPE). The established NADES-based MDMSPE was combined with inductively coupled plasma optical emission spectrometry (ICP OES) to determine Pb and Cu in natural medicine Polygonatum kingianum Coll. Et Hemsl (P. kingianum) for the first time, using the Fe₃O₄@TiO₂@NADES composite as a sorbent. The composite was characterized by using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), vibrating sample magnetometry (VSM), transmission electron microscopy (TEM) and the Brunauer–Emmett–Teller (BET) specific surface area. Various parameters affecting MDMSPE were evaluated. The optimum conditions were 4 min of adsorption, 55 mg of adsorbent, pH 7, and 14 min of elution. Under the optimal conditions, the enrichment factors (EFs) of Pb and Cu were 24 and 32, the limits of detection (LODs) were 0.21 and 0.08 μg L⁻¹, and the limits of quantification (LOQs) were 0.67 and 0.24 μg L⁻¹, respectively. This method was applied to analyze the natural drug P. kingianum, and the results were found to be in good agreement with those determined by inductively coupled plasma mass spectrometry (ICP-MS), demonstrating the reliability in determining Pb and Cu in the samples.