激光剥蚀-等离子体质谱技术及其在地球化学宇宙化学和环境研究中的应用_JOCHUM Klaus Peter.pdf

2009年2月 February 2009 石矿测试 ROCK AND MINERAL ANALYSIS Vol. 28 , No. I 53 68 文章编号0254 -5357200901 -0053 -16 Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry and Its Application in Geochemistry, Cosmochemistry and Environmental Research JOCHUM Klaus Peter, STOLL Brigitte, FRIEDRICH Jon M23, AMINI Marghaleray“4, . 7 BECKER Stefan5 , DuCKtNG Marc5, EBEL Denton S2, ENZWEILER Jacinta6, HU Ming-yue KUZMIN Dmitryo, MERTZ-KRAUS Regina08, MuLLER Werner E G9, REGNERY Julia, SOBOLEV Alexande/1.1 , WANC Xiao-hong.7 , ZHAN Xiu._chun7 1. Max Planck-Institut fur Chemie, Mainz 55020, Germany; 2. Department of Earth and Planetary Sciences, American Museum of Natural History, New York 10024, USA; 3. Department of Chemistry, Fordham University, Bronx,New York 10458, USA; 4. Saskatchewan Isotope Laboratory, Department of Geological Sciences, University of Saskatchewan, Saskatoon S7N SE2, Canada; 5. Bundeskriminalamt, Wiesbaden 65173, Germany; 6.lnstituto de Geociencias, University of Campinas, CP 6152 Campinas, CEP 13083-970, Brazil; 7. National Research Center for Geoanalysis, Beijing 100037, China; 8.lnstitut fur Geowissenschaften, Universitat Mainz, Mainz 55099, Germany; 9.lnstitut fur Physiologische Chemie, Universitat Mainz, Mainz 55099, Germany; 10. Institute of Geology and Mineralogy, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090, Russia; 11. V. I. Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, Moscow 119991, Russia Abstract Laser ablation LA -inductively coupled plasma-mass spectrometry ICP-MS has become one of the most important s for in situ trace elemental and isotopic analysis in geochemistry, cosmochemistry and enwronmental research. For these purposes, different kinds of mass spectrometers and lasers are used, which are presented in this paper. One of the most useful LA-ICPMS instruments is the combination of a single-collector sector field mass spectrometer with Nd YAG laser ablation systems 193 nm and 213 nm wavelengths, respectively. This design used in the MPI Mainz laboratory is described in detail in this paper. Data optimization techniques including diverse correction procedures are also discussed. To demonstrate the power of LA-ICPMS, several applications of trace elemental and isotopic analysis are presented, such as investigations of reference materials, trace element analysis in Hawaiian basalts, Martian meteorites, biological spicules and corals, as well as Pb and Sr isotope measurements of melt inclusions and Ca-Al rich inclusions of carbonaceous chondrites. Key words laser ablation-inductively coupled plasma-mass spectrometry LA-ICPMS ; geological sample; reference material; meteorite; biological sample; trace element; isotope ratio 收稿日期 作者简介 2008-05-26 ;修订日期 2008-08-07 JOCHUM Klaus Peter, major in trace element and isotope geochemistry mainly oceanic basalts, meteorites, environmental and biological samples , LA-ICPMS, investigations of reference materials, GeoReM database. E-mail kpj mpch-mainz. mpg. de。 - 53 - ChaoXing 第1期 2009年 激光剥蚀 一 等离子体质谱技术及其在地球化学宇宙化学和 环境研究中的应用 摘要激光剥蚀 一等离子体质谱 LA -ICPMS已成为地球化学、宇宙化学和环境研究领 域元 素和同位素原位分 析最重要的技术之一。文章介绍了多种类型的质谱仪及其使用的激光器。用途最广的LA - ICPMS 仪器之一是 单接收器扇形磁场质 谱仪 ，配有NdYAG激光剥蚀系统（激光波长分为193 nm和213 nm两种） ，MPI Mainz实验 室使用的就是这套系统，文章对 此作 一详细介绍 。文中阐述了数据优化技术及其多种校正过程；介绍 LA - ICPMS 在痕量元素和同位素分析领域的一些应用 ，包括参考物质的研制，Hawaiian玄武岩、Mafiian 陨石 、 生物骨针和珊瑚虫中 痕量元 素分 析及 熔融包裹体和富钙 一铝碳质球粒 陨石 中的铅和锶同位素测量。 关键词激光剥蚀 一 等离子体质谱； 地质 样品；参考物质；陨石；生物样品；痕量元素；同位素比值 中图分类号0657. 63 文献标识码A 1 Introduction Laser ablation-inductively coupled plasma mass specLrometry LA-ICPMS has become a powerful analytical. technique used in nearly all subdisciplines of geochemical, cosmocherrncal and environmental research[]. Ihe growth of LA-ICPMS can be seen by an uation of recent publication history over the last decade. For example, there has been steady increase of the number of publications in the Joumal of Analytical Atomic Spectrometry JAAS from 4 in the year 1995, t0 18 in 2001 and then t0 40 in 2007. A recent review2l, noted that the use of LA-ICPMS has substantially increased and it concluded that the trend will continue for the foreseeable future. Additionally, the top 20 most frequently requested reference materials of the GeoReM database http//georwn. mpch-mainz. mpg. de[31 comprise 12 reference glasses from the National Institute of Standards and Technology NIST, the United States of Geological Survey USGS and the Max-Planck-Institut fi.ir Chemie MPI-DING mainly used as calibration materials for LA-1CPMS and other microanalytical techniques. 2 Types of LA-ICP Mass Spectrometers There are a variety of lasers and mass spectrometers that are used for LA-ICPMS analysis. Each of their analytical features differs and they are used for applications with various requirements, such as routine trace element, high-precision isotopic analysis, or bulk and micro analysis of geological, biological and environmental samples. The commonly used mass spectrometers and lasers are compared in Table l and Table 2 and explained below. 2.1 Quadrupole Mass Spectrometers Quadrupole mass spectrometers apply voltages on four parallel metal rods affect the trajectory of ions extracted from the ICPs plasma. Only ions of a - 54 - certain mass pass through the quadrupole, which can be considered as a mass filter. Quadrupole mass spectrometers have the advantages of extremely fast scan times e. g. 0. 25 s for the determination of 25 trace elements and are relatively small, low-cost systems. The primary disadvantages are the low mass resolution about 300 of the quadrupole and the non-flat triangular peak shape, which does not allow for precise isotope ratio measurements. Table l The commonly used ICP-MS ┏━━━━━━━━━┳━━━━━━┳━━━━━━━━━━━━━━━━━━┳━━━━━━━━━┓ ┃ ┃ ┃ mass spectrometers ┃ ┃ ┣━━━━━━━━━╋━━━━━━╋━━━━━━━━━┳━━━━━━━━╋━━━━━━━━━┫ ┃ parameters ┃ ┃ single collector ┃ ┃ multicollector ┃ ┃ ┃ quadrupole ┃ ┃ time-of-flight ┃ ┃ ┃ ┃ ┃ sector-field ┃ ┃ sector-field ┃ ┣━━━━━━━━━╋━━━━━━╋━━━━━━━━━╋━━━━━━━━╋━━━━━━━━━┫ ┃ scan time from ┃ ┃ eleccrical scan ┃ ┃ ┃ ┃ one mass ┃ fast ┃ fast, magnetic ┃ verV fast ┃ scanning is not ┃ ┃ ┃ ┃ ┃ ┃ usu.al, very slow ┃ ┃ to another ┃ ┃ scan slow ┃ ┃ ┃ ┣━━━━━━━━━╋━━━━━━╋━━━━━━━━━╋━━━━━━━━╋━━━━━━━━━┫ ┃ ┃ 300 400 ┃ 300 10000 ┃ 500，2 000 ┃ 300 ┃ ┣━━━━━━━━━╋━━━━━━╋━━━━━━━━━╋━━━━━━━━╋━━━━━━━━━┫ ┃ peak shape ┃ triangular ┃ flat top ┃ triangular ┃ flat Lop ┃ ┣━━━━━━━━━╋━━━━━━╋━━━━━━━━━╋━━━━━━━━╋━━━━━━━━━┫ ┃ sensitivity ┃ medium ┃ ┃ ┃ ┃ ┃ cps/ppm ┃ to high ┃ high ┃ low ┃ high ┃ ┣━━━━━━━━━╋━━━━━━╋━━━━━━━━━╋━━━━━━━━╋━━━━━━━━━┫ ┃ ┃ elementai ┃ elemenLal and ┃ fast scanning ┃ high-precision ┃ ┃ appLications ┃ ┃ ┃ ┃ ┃ ┃ ┃ analysis ┃ isotopic analysis ┃ capahilicy ┃ isolopic analysis ┃ ┗━━━━━━━━━┻━━━━━━┻━━━━━━━━━┻━━━━━━━━┻━━━━━━━━━┛ Table 2 Lasers commonly used for laser ablation ┏━━━━━━━━━━━━━━━━━━━━━━━━━━━┓ ┃ ┃ ┣━━━━━━━━━━━━━━━━━━━━━━━━━━━┫ ┃ parameters ┃ ┣━━━━━━━━━━━━━━━━━━━━━━━━━━━┫ ┃ Nd YAC Nd YAC Nd YAC ArF excimer fs laser ┃ ┗━━━━━━━━━━━━━━━━━━━━━━━━━━━┛ wavelength nm 266 pulse energy mj 0.5 4 pulse width 9 ns repetition rate Hz 1 20 crater diameter ym 3 80 213 0.2 2 5 ns 1N 20 2 N 160 193 0.1 1 3 ns 1 N IO 5 N100 193 0. 05 0. 8 15 ns 1 N 100 4 N 200 196 800 14 60 400 fs 1 N 10 5 N100 2.2 Single-collector Sector-field Mass Spectrometers Single-collector sector-field mass spectrometers, which contain magnetic and electric sector fields, are used for sensitive LA-ICPMS trace element analyses. The magnetic sector field separates ions according to their mass-to-charge ratio, whereas the electric sector 咖 式 n ‘ “ 测 如 矿 一 岩 ∥ 5 ChaoXing 第 1期 JOCHUM Klaus Peter, et alLaser Ablation-Inductively Coupled Plasma-Mass Spectrometry and Its Application ... 第 28卷 focuses ions according to their kinetic energy. Because of the developments of fast magnets, reasonable scan times about l 2 s can be obtained for the LA-ICPMS analysis of 40 50 trace elements. The major advantage is the potential for high mass resolution up t0 10000 to separate masses of interest from disturbing molecular interferences. Most analysts, however, use the low mass resolution mode 300 that yields flat-top peaks to obtain highly sensitive elemental analyses and relatively precise isotope ratio measurements. As a trade off between resolution and sensitivity, some laboratories compromise with a mass resolution of about 4000 for their LA-ICPMS analyses, which does allow the separation of many mass lines of interest from disturbing molecule lines. 2.3 Time-of-Flight Mass Spectrometers Time-of-flight mass spectrometers TOF-MS measure the mass-dependent time and it takes ions of different masses Lo move from the ion source to the detector. This requires that the starting time the time at which the ions leave the ion source is well- defined. This type of mass spectrometer is only used in some LA-ICPMS laboratories[4]. The major advantages include the fast speed of acquisition and high ion transmission. However, the dynamic range of the instruments is limited. Due to their relatively low sensitivity, TOF mass spectrometers have higher detection limits than quadrupole instruments. 2.4 Multi-collector Sector-field Mass Spectrometers Similar to the mass spectrometers described above in chapter 2.2, multi-collector sector-field mass spectrometers consist of magnetic and electric field sectors. However, multiple collectors are used for the simultaneous measurements of ions. Because of this and the consistent mass bias variation across the mass range, highly precise isotope ratios can be obtained. Disadvantages include the low mass resolution of most instruments, which can lead to significant interferences caused by doubly charged ions, oxides and argdes. Faraday cups are generally used and therefore only isotopes of high-abundant elements e. g. ca. 50 yg/g for Pb, ca. 500 yg/g for Sr can be measured with high precision. Because of the slow switching, but very stable magnets used, MC-ICPMS instruments are not suitable for multi-element analysis. 2.5 NdYAG Lasers NdYAG lasers are widely used in LA-ICPMS laboratories. Early LA-ICPMS systems used the fundamental wavelength of 1064 nm, which is poorly absorbed by many minerals. Therefore, new developments in NdYAG lasers led to the use of harmonic wavelengths of 532 nm, 266 nm, 213 nm and 193 nm. With shorter wavelengths, srualler particles are produced and there is a higher absorption of the laser energy in the surface layers of materials. Like the wavelength, pulse length has a considerable influence on the quality of the results-shorter pulses increase the energy deposited in the area to be analyzed. State-of-the-art Nd YAG lasers typically employ wavelengths of 193 nm or 213 nm and pulse lengths of 3 5 ns. Laser ablation systems using Nd YAG lasers are relatively compact. 2. 6 ArF Excimer Lasers ArF excimer lasers have a short wavelength of 193 nm producing less severe fractionation effects because of almost complete vaporization and excitation of all ablated particles in the ICP 5-. Very flat crater shapes can be obtained using these lasers. However, the longer pulse lengths about 15 ns compared to the NdYAG lasers and the much Jarger size of the instruments have left this as a less-used option for IA-ICPMS. 2.7 Femtosecond fs -Lasers At present, femtosecond fs -laser is only applied to LA-ICPMS in some laboratories[6]. Due to the fs time scale, ablation is essentially non-thermal. This is important for complex matrices, where the elemental fractionation is similar. A Ti sapphire laser having 800 nm and more recently 260 nm has been used in fs laser ablation studies. 3 Results and Discussions 3.1 Measurement Procedures Different procedures have been used to convert the count rates and the voltages for the ions in element abundances and isotope ratios, respectively. It is beyond the scope of this paper to explain and to uate all these procedures for the different combinations of ICP mass spectrometers and laser ablation systems. The uation technique as used in the MPl Mainz laboratory will be elaborated as follows. In this laboratory, LA-ICPMS analyses are pered with the single-collector sector-field ICP mass spectrometer ThermoFinnigan Element 2, which is connected alternatively with the UP213 0r the UP193SS Nd YAG laser ablation system from New Wave[9]. Such combinations have also been used in many other laboratories worldwide and have delivered highly sensitive and precise trace element and isotope data. Typical instrumental parameters of the mass spectrometer and the laser ablation systems are listed in Table 3. For most measurements the low mass resolution mode mass resolution 300 of the ICP-MS is used. Routine trace element analyses are pered using the combination of magnetic B scan and electric scan E scan modes of the Element 2. Scan times for the determination of 40 50 trace elements are about l.5 s. This means that - 55 - ChaoXing 第1期 岩矿测试 http∥www. ykcs ．ac．cn 2009年 during a l minute analysis of a single spot, about 40 scans can be pered. For isotope analysis of Pb and Sr only the E scan mode is used allowing a quasi simultaneous determination of 1 000 2 000 scans during a l min ablation period. Table 3 Typical operating parameters parameters New Wave laser ablation