Determination of rare earth elements in geochemical samples by inductively coupled plasma mass spectrometry after digestion in micro-open system
Rare earths are a key focus of geological exploration work and a new round of strategic explora-tion breakthroughs.The accurate determination of contents of rare earth elements in geochemical samples is very important.In this study,the sample was digested with nitric acid-hydrofluoric acid-perchloric acid-sulfuric acid system using an electric graphite digestion device equipped with polytetrafluoroethylene diges-tion tube.The determination of rare earth elements in geochemical samples by inductively coupled plasma mass spectrometry(ICP-MS)after digestion in micro-open system was realized.The results showed that the sample could be fully digested in micro-open system under the following conditions:the dosage of nitric acid-hydrofluoric acid-perchloric acid-sulfuric acid system was 8 mL;the highest digestion temperature was 240 ℃,which was kept for 2.5 h(total digestion time of 4.5 h).The linear correlation coefficients of cali-bration curves were all greater than 0.999.The limits of detection of this method were 0.001-0.03 μg/g,and the limits of quantification were 0.004-0.12 μg/g.The limits of detection for most rare earths in ex-periments were lower than those obtained by standard method DZ/T 0279.32-2016 and GB/T 14506.30-2010.The contents of rare earths in certified reference materials of stream sediment,soil and rock were determined according to the experimental method.The results showed that the logarithmic difference(Δlg(C))between the measurement values and certified values of elements was 0.00-0.03,and the relative standard deviations(RSD,n=6)were between 0.74％and 7.2％,which could meet the requirements ofΔlg(C)≤0.11 and RSD≤10％specified in DZ/T 0011-2015.The rare earth elements in certified reference materials of rock and soil were determined according to the experimental method and ICP-MS after acid dis-solution in closed system.The measurement results of two methods were basically consistent.The acid consumption in this method was low and the sample digestion time was short.It could be used for the batch test of rare earth elements in geochemical samples.
rapid digestion in micro-open systeminductively coupled plasma mass spectrometry(ICP-MS)geochemical samplesrare earth element
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