Optimization And Application Of LA-ICPMS Technology

Laser ablation inductively coupled plasma mass spectrometry is a new instrument by laser ablation system and inductively coupled plasma mass spectrometry(GC English abbreviated as LA-ICPMS),the analysis is in situ,real-time analysis and advantages of high sensitivity,better spatial resolution etc.Although LA-ICPMS solid in situ analysis is widely used,but the accurate analysis of elements in geological samples is still restricted by many factors,such as instrument conditions,fractionation with the sample matrix composition changes,matrix matching standard material shortage,quantitative calculation method and the effective sensitivity drift correction.On the basis of LA-ICPMS zircon U-Pb dating of the normal operation of a number of years,based on the analysis of LA-ICPMS technology optimization,including replacing the conventional instrument with the ablation cell is a rotary type double channel erosion pool,air flow in the plasma Center(Ar+He)to add a small amount of nitrogen gas(gas flow rate is 2.5 ml/min),increased signal viscolizer and other measures to improve the sensitivity and reduce the detection limit and improve analysis precision.Using the optimized LA-ICPMS analysis technique,the small particle zircon U-Pb dating of the laser beam spot of 24 ?m and 16 ?m was carried out.Using NIST SRM 610 as the correction elements in the samples with 91500 international standard zircon age corrected value,with Zr91 as the internal standard element,the laser beam is three class standard Plesovice,Mud and Tank zircon Qinghu 206Pb/238 U age weighted average values were 337.0±3.1 Ma?732.0±6.8 Ma?158.2±1.6 Ma under 24 ?m conditions,the laser beam spot is 16 ?m three Plesovice,Tank and Mud standard zircon Qinghu 206Pb/238 U age weighted average values were 339.6±4.1 Ma?732.9±8.1 Ma?159.8±1.8 Ma,the results agree well with the recommended values,the small laser beam class developed in our laboratory zircon U-Pb dating method is feasible.The laboratory also carried out the test of the main trace elements in silicate.By using the optimized LA-ICPMS analysis technology,the laser beam diameter is 44 ?m,the frequency is 5 Hz,BCR-2G,BIR-1G,the molten glass on the ATHO-G,GOR132-G,T1-G and St Hs6/80-G of the six international standard material of LA-ICPMS 10 major elements and 47 kinds of trace element analysis.The same set of data to NIST SRM 610,GSE-1G and MPI-DING international standard material for outer standard,using Ca as the normalized elements,respectively by internal standard method and the correction strategy for Ca internal standard method,comparing the 6 sets of results obtained for each sample,the results show that the establishment of the laboratory Portland LA-ICPMS single mineral trace elements test method is feasible,compared the different correction strategies the results of difference and discusses its possible causes.In addition,the test of the main trace elements in carbonate is also attempted.In NIST SRM 610,GSE-1G and MPI-DING international standard material made by laser beam spot external standard 44 ?m,60 ?m,laser frequency 5 Hz,and using Ca as internal standard correction strategy with no internal standard method of carbonate MACS-3 international standard material were tested and analyzed the major and the trace elements.The analysis results show that most of the elements test value and recommended value of relative error(RE)in less than 20%,the relative standard deviation(RSD)is less than 10%,at the same time we use no internal standard method can accurately determine the main content,carbonate trace elements,which suggests that the taste of carbonate rock major and trace elements of LA-ICPMS the establishment of the in-situ test method design feasibility.