Development Of Calibration Material For LA-ICP-MS Of Carbonate Minerals

Laser ablation inductively coupled plasma mass spectrometry(LA-ICP-MS)is a technique for in situ micro-analysis of solid samples with high sensitivity,high spatial resolution,wide detection range,low injection volume,low baseline background value and other advantages.Reliable reference materials are the precondition for obtaining accurate analytical data by LAICP-MS.However,in the LA-ICP-MS analysis and testing work,the number of carbonate standard samples that can meet the needs of analytical research and application is insufficient and incomplete.The lack of carbonate standard materials restricts the development of technology and seriously hinders the wide application of LA-ICP-MS in quantitative analysis of carbonate.In this paper,the development of standard carbonate materials is taken as the goal,and the natural rare earth carbonate samples in Baiyun Obo mining area are used as raw materials.They are rare earth tailings,dolomite,high-grade rare earth ores and low-grade rare earth ores.Ammonium bicarbonate and ammonia water are selected as precipitants.The calibration materials are prepared by chemical coprecipitation method,and the calibration materials are tested and analyzed by various technical means.The main results are as follows:1.It is feasible to prepare calibration substance of carbonate powder by chemical coprecipitation from natural rare earth carbonate of Bayan Obo.2.X-ray diffraction,laser Raman spectroscopy,X-ray fluorescence spectroscopy and other methods of overall analysis indicate that the calibration materials prepared by coprecipitation are composed of carbonates.3.The LA-ICP-MS technology and mathematical statistics method are used to check the homogeneity of the calibrated substances.The results show that most elements within and between the calibrated substance units meet the requirements of homogeneity test,and the homogeneity is good.Among them,except for the contents of Si,K,Ti,Cr,Co,Ge,Sn and Lu in different samples,the contents of the other elements in the tablets are relatively small,with the relative standard deviation less than 15% and rare earth elements generally less than 10%.The relative standard deviation of the contents of Si,K,Co,Ga and Ge in the tablets is slightly greater than 20%.The content of other elements is consistent.4.The LA-ICP-MS technology is used to preliminarily determine the calibration material,the results are good as a whole.5.Carbonate calibration materials prepared by co-precipitation method can be used as internal or external reference materials for microanalysis.Especially,the content of rare earth elements in calibration material is suitable,which can meet the quantitative analysis of trace elements in rare earth carbonate.