Polymer monolith microextraction coupled to microwave plasma torch–atomic emission spectrometry for the determination of Nd, Eu and Yb in tea samples

Abstract

A reliable and rapid method based on polymer monolith microextraction (PMME) combined with microwave plasma torch-atomic emission spectrometry (MPT-AES) was established for the determination of trace rare earth elements (REEs), Nd (light), Eu (medium) and Yb (heavy). Several parameters affecting extraction efficiency, including sample pH, sample flow rate, sample volume, eluent concentration, eluent flow rate and eluent volume, were investigated and optimized in detail. Under the optimum conditions, the limits of detection (n = 7) and limits of quantification (n = 7) for Nd, Eu and Yb (based on a 0.8 mL sample volume) were determined to be 1.07, 0.83 and 1.47 μg L⁻¹, and 3.57, 2.78 and 4.90 μg L⁻¹, respectively. The enrichment factors for Nd, Eu and Yb (5 μg mL⁻¹) were determined to be 15.1, 12.8 and 12.5, respectively, with relative standard deviations (n = 7) of 5.10%, 5.43% and 7.84%. The proposed method has been successfully applied to the analysis of Nd, Eu and Yb in tea samples with a recovery range of 81.2–109.2%.