Determination Of Trace Elements In Silicate Samples Using LA-ICP-MS Combined With Flux-free Fusion Sample Preparation

Quantitative analysis of trace elements is a key issue in analytical chemistry research,and Laser Ablation Inductively Coupled Plasma Mass Spectrometry?LA-ICP-MS?is widely used in micro-area analysis because of its high efficiency and low contamination.However,the LA-ICP-MS is well-understood,there are few applications in the analysis of trace elements at geological whole rock samples compared with traditional Solution-ICP-MS.Therefore,it is necessary to study the method of accurate analysis of trace elements in whole rock samples by LA-ICP-MS technology for making trace elements analysis more convenient and efficient.In this method,the main reasons that affect the accuracy of the results are the preparation of whole rock sample,the elemental fractionation effect,and the matrix effect between the standard materials and the unknown samples.Considering the above problems,this study took silicate whole rock samples as the research object,and prepared silicate molten glass?GSR-3,BHVO-2,BCR-2?of whole rock samples by flux-free fusion,moreover optimized the conditions of LA-ICP-MS to reduce the elemental fractionation effect on the results,then improved the accuracy of the results by external standard correction combined with internal standard normalization.In addition,the LA-ICP-MS and Solution-ICP-MS methods were applied to molten glass and whole rock powder,respectively,the content of Sr,Y,Zr,Nb Hf,U,Th,Pb,REEs was analyzed to evaluate the feasibility of the method.This study got the optimal laser repetition rate,beam spot diameter and energy density were 6Hz,60?m,and 8J/cm²,respectively.For the elements analyzed,the relative deviation?RE?between the measured results and the recommended value is within 10%under the condition that NIST610 and GSD-1G were used as external standard materials and ⁴⁴Ca was used as the internal standard element.And a relatively homogeneous molten glass can be obtained at10 min by molybdenum sheet wrapping-no flux-tube furnace melting-Ar gas protection method.With the exception of Pb,the relative standard deviation?RSD?of all analyzed elements was less than 10%,and the RE of the most elements was better than 10%?except Pb,Tm,Lu?.Comparing the analysis results of LA-ICP-MS and Solution-ICP-MS,except for individual low-content trace elements such as Tm,Lu and volatile elements Pb,the results of the two methods were consistent,even the LA-ICP-MS analysis results of some elements were better than the Solution ICP-MS The flux-free fusion technology combined with LA-ICP-MS established in this research has a detection limit of 0.015?g/g?11.8?g/g;a measurement range of 0.045?600?g/g;the accuracy of most elements is excellent at 10%,and precision is better than 5%.This method guarantees the accuracy of the results,and avoids the chemical digestion.