InertSep ME-2螯合树脂固相萃取-电感耦合等离子体质谱法测定海水中稀土元素OA北大核心

Rare earth elements(REEs)serve as excellent tracers for indicating the sources and evolutionary pro-cesses of substances in the ocean.Nevertheless,the concentration of REEs in seawater is exceedingly low,meas-ured in picomoles per kilogram,and the presence of high salinity in the seawater matrix introduces substantial challenges for accurate measurement.This study developed a method for enriching trace REEs in seawater using a novel chelating resin(i.e.,InertSep ME-2)coupled with inductively coupled plasma mass spectrometry for meas-urement.This study also conducted structural characterization of the chelating resin material and explored the mechanism of REE enrichment by the resin.X-ray photoelectron spectroscopy analysis showed that InertSep ME-2 resin is mainly composed of the elements C and O.Fourier transform infrared spectroscopy showed that the resin adsorbs Lu and exhibits a characteristic peak generated by the twisted vibration of carboxylate ions at 657 cm-1,indicating that REEs are adsorbed in the form of carboxylate salts in the resin.The experimental results showed that the best enrichment effect was achieved when the pH of the seawater sample was adjusted to 5.0-5.1,with 12 mL of 0.4 mol/L NH4Ac used to remove salts,2 mL of 2 mol/L HNO3 used as the eluent,and 3-6 mL/min set as the sam-ple injection speed.The recovery rate of this method for REE enrichment in seawater ranged from 92%to 103%,with detection limits ranging from 0.000 25 pmol/kg to 0.054 pmol/kg.The precision of the analysis was less than 5%(n=6).The accuracy of the method is verified to be high using the NASS-7 standard seawater,and the differ-ence between the measured concentration and the literature average is within one standard deviation range.The method established in this study can be used to determine REE concentrations in low-salinity river water,estuarine salinity gradient zones,and high-salinity seawater samples.