Dandelion pollen-like 3D hierarchical CoFe2O4 porous microspheres for magnetic dispersive solid-phase microextraction/ICP-OES quantification of fourteen rare earth elements (REEs) from water, fennel, and rosemary.

Most magnetic dispersive solid-phase microextraction (M-D-SPµE) adsorbents have certain drawbacks including difficult synthesis, high contact times and low selectivity. Therefore, in this work, a dandelion pollen-like CoFe2O4 magnetic nanomaterial (DP-M-CoFe2O4) was synthesized. The M-D-SPµE coupled with ICP-OES was first developed to determine 14 REEs in herbs and waters. The factors affecting M-D-SPµE of the 14 REEs using DP-M-CoFe2O4 were examined. The contact times for adsorption/elution, preconcentration factor (PF) and linearity of the method were found to be 1 min/30 s, 12.5, and 5-500 µg L-1, respectively. The limits of detection (LODs) and the relative standard deviations (RSDs) of 14 REEs changed from 0.005 µg L-1 (Eu) to 0.126 µg L-1 (Sm) and from 1.92% (La) to 3.46% (Sm). The M-D-SPµE has high selectivity. The accuracy of M-D-SPµE was verified by recovery studies in NW-TMDA-54.6 Lake Water, LGC6016 Estuarine Water, water, and herbs, with recoveries ranging from 88% to 111%. The method showed fast adsorption and elution times, comparable linear ranges, low limits of detection, high selectivity and high precision to existing ICP-OES methods. By using M-D-SPµE-ICP-OES, the 14 REEs were successfully determined in tap water, dam water, wastewater, well water, seawater, fennel, and rosemary.