Research on Pretreatment Methods for ICP-MS Determination of the Associated Critical Three Rare Elements in Kaolinite Clay Rock Minerals in the Adjacent Areas of Sichuan,Yunnan,and Guizhou
There is a set of weathering crusts with relatively stable thickness between the top of Mount Emei basalt and the bottom of the Xuanwei Formation in the adjacent areas of Sichuan,Yunnan,and Guizhou,it is en-riched with three rare elements and mainly composed of Kaolinite clay rock.In order to find out its ore grade and content,this study used X-ray diffraction(XRD)to analyze the mineral composition,and X-ray fluorescence(XRF)to analyze the major and trace elements.Several different pre-melting treatment methods were used for comparison,and the test solution was determined by inductively coupled plasma-mass spectrometry(ICP-MS).The test results show that:①The mineral composition sample mainly consists of kaolinite,anatase,illite,ilmen-ite,brookite,etc.,of which kaolinite accounts for 62.3％to 89.85％,anatase accounts for 2.50％to 11.8％,illite accounts for 1.8％to 18.0％,ilmenite accounts for 0.10％to 1.00％,and brookite accounts for 0.70％to 7.00％.Its major elements are Si,Al,Fe,and Ti.②High-pressure closed microwave dissolution method is suitable for the dissolution of the concomitant rare earth element Sc,but for Nb and Zr,the data show a lower trend,while differences in other elements are not significant.③Alkali fusion-precipitation separation method is suitable for the decomposition of the insoluble metal minerals,which not only opens the mineral lattice but also effectively purifies the test solution through the use of precipitant or test complexing agents.It effectively reduces matrix in-terference and improves data accuracy.The method is suitable for the pre-treatment of elements Pr,Nd,Tb,Dy,Nb,and Zr.④Alkali fusion-acidification of fused material is suitable for the pre-fusion treatment of the sper-sed element Ga.By using kinetic energy discrimination(KED)mode,it effectively reduces spectral interference and improves the accuracy of Ga determination.The detection limit of the system method ranged from 0.011 pg/g to 1.66 pg/g,the lower limit of determination ranged from 0.044 pg/g to 6.65 pg/g.The relative stand-ard deviation(RSD)ranged from 2.06％to 11.1％,and the relative error(RE)ranged from 0.99％to 9.90％.Verified by sample testing,the methods above were found to be suitable for the determination of the associated critical three rare elements in kaolinite clay rocks in the studied region.
Three rare elementsAlkaline dissolving methodHigh-pressure microwave digestion methodInductively coupled plasa mass spectrometry(ICP-MS)
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