Determination of total amount of rare earth elements and its component in iron concentrate by inductively coupled plasma mass spectrometry with microwave digestion
The accurate determination of total amount of rare earth elements and its component in iron con-centrate is of great significance for the comprehensive utilization of iron concentrate.In this study,the iron concentrate sample was dissolved by microwave digestion with 6 mol/L HC1.Iron(Ⅲ)in matrix was ex-tracted with methyl isobutyl ketone to overcome the matrix effect.The internal standard correction was conducted with 50 ng/mL Re.The total amount of rare earth elements and its component in solution were determined by inductively coupled plasma mass spectrometry(ICP-MS)using standard mode.The deter-mination of total amount of rare earth elements and its component in iron concentrate was realized.The in-fluence of matrix effect on the determination was investigated.The results showed that the recoveries of rare earth elements were between 6％and 31％if the sample was directly determined by ICP-MS after mi-crowave digestion,implying that the influence of matrix effect on the determination could not be ignored.After microwave digestion,the iron matrix was removed by methyl isobutyl ketone extraction.Then the solution was determined by ICP-MS,and the recoveries of rare earth elements were between 96％and 103％.Therefore,before determination,the methyl isobutyl ketone extraction was adopted after digesting the sample to separate the iron matrix from testing elements.Under the optimal experimental conditions,the mass concentration of rare earth elements in range of 5-100 ng/mL showed a good linear relationship with the corresponding MS signal intensity.The correlation coefficients(r)of calibration curves were be-tween 0.999 2 and 0.999 9.The limits of detection of method were between 0.000 1 ng/mL and 0.060 5 ng/mL.The proposed method was applied for the determination of total amount of rare earth elements and its component in iron concentrate.The relative standard deviations(RSD,n=6)of determination results were between 2.3％and 4.2％.The spiked recoveries of total amount of rare earth elements and its com-ponent were between 92％and 108％,which could meet the analysis requirements on spiked recovery in national geological and mineral industry standard DZ/T 0130-2006.
iron concentratemicrowave digestionrare earth elementsinductively coupled plasma mass spectrometry(ICP-MS)
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