Determination of Trace Elements in Calcite Using Solution and Laser Ablation ICP-MS: Calibration to NIST SRM Glass and USGS MACS Carbonate, and Application to Real Landfill Calcite

We report new data on the trace element concentrations of Mg, Cr, Mn, Co, Ni, Cu, Zn, Sr, Cd, Ba, La, Ce, Nd, Pb and U in USGS carbonate reference materials (MACS-1 and MACS-2) and compare solution ICP-MS and LA-ICP-MS trace element determinations on landfill calcites using calibration to different reference materials (MACS-1 and MACS-2 carbonate and NIST SRM 612 glass). Very good agreement (differences below 10% relative) was found between laser ablation and solution ICP-MS data for MACS-1 with higher concentrations of trace elements (values between 100 and 150 μg g⁻¹), with the exception of Cu and Zn. Similarly good agreement was found for MACS-2 with lower trace element concentrations (units to tens of μg g⁻¹), with the exception of Cr, Co and Zn. The MACS-1 reference material for calibration of LA-ICP-MS was found to be extremely useful for in situ determination of trace elements in real-world carbonate samples (landfill calcites), especially those present in calcite in higher concentrations (Mn, Sr, Ba; < 5% RSD). Less accurate determinations were generally obtained for trace elements present at low concentrations (∼ units of μg g⁻¹). In addition, good agreement was observed between the instrument calibration to MACS and NIST SRM 612 glass for in situ measurements of trace elements in landfill calcites K-2, K-3 and K-4 (differences below 15% relative for most elements). Thus, the application of MACS carbonate reference materials is promising and points to the need for the development of new carbonate reference materials for laser ablation ICP-MS.     

Laser Ablation ICP-MS Analysis of Geological Materials Prepared as Lithium Borate Glasses

A simple, rapid and precise method is described for determining trace elements by laser ablation (LA)-ICP-MS analysis in bulk geological materials that have been prepared as lithium borate glasses following standard procedures for XRF analysis. This approach reliably achieves complete sample digestion and provides for complementary XRF and LA-ICP-MS analysis of a full suite of major and trace elements from a single sample preparation. Highly precise analysis is enabled by rastering an ArF excimer laser (λ= 193nm) across fused samples to deliver a constant sample yield to the mass spectrometer without inter-element fractionation effects during each analysis. Capabilities of the method are demonstrated by determination of twenty five trace elements (Sc, Ti, V, Ga, Rb, Sr, Y, Zr, Nb, Cs, Ba, REE, Hf, Ta, Pb, Th and U) in a diverse range of geological reference materials that includes peridotites, basalts, granites, metamorphic rocks and sediments. More than 90% of determinations are indistinguishable from published reference values at the 95% confidence level. Systematic bias greater than 5% is observed for only a handful of elements (Zr, Nb and U) and may be attributed in part to inaccurate calibration values used for the NIST SRM 612 glass in the case of Zr and Nb. Detection limits for several elements, most notably La, are compromised at ultra-trace levels by impurities in the lithium borate flux but can be corrected for by subtracting appropriate procedural blanks. Reliable Pb analysis has proved problematic due to variable degrees of contamination introduced during sample polishing prior to analysis and from Pt-crucibles previously used to fuse Pb-rich samples. Scope exists for extending the method to include internal standard element/isotope spiking, particularly where integrated XRF analysis is not available to characterise major and trace elements in the fused lithium borate glasses prior to LA-ICP-MS analysis.     

Application of Laser Ablation ICP-MS to U-Th-Pb Dating of Monazite

Recent advances in laser ablation ICP-MS techniques allow accurate U-Th-Pb age dating of monazites that are as young as several tens of million years to a precision better than 2%. Accuracy of the age determinations has been improved by true real-time mass bias correction via nebulisation of a solution containing enriched ²³³U and natural Tl isotopes. The Tl-U tracer solution eliminates possible effects of variable sample matrices on the precision and accuracy of measured isotopic ratios. Mass bias corrections based on measured ²⁰⁵Tl/²³³U ratios in the tracer solution allow direct measurement of ²³⁵U in monazite. Combined with high-sensitivity laser ablation ICP-MS measurements, direct measurement of ²³⁵U particularly improves the precision of U-Pb dating of young monazites. Correction for laser-induced Pb/U and Pb/Th elemental fractionation is based on a mathematical treatment of time resolved count-rate data that is independent of laser ablation characteristics, does not require external standardisation and allows variable laser pit size or raster patterns for each measurement. The new procedures make the LA ICP-MS technique more flexible for in situ U-Th-Pb analysis.     

等离子体质谱法测定天然水中痕量元素

本文利用ICP-MS分析技术检出限低,可同时测定多元素,以及溶液进样等特点,建立了天然水中多种痕量元素分析的有效方法,研究了整个测定质量范围内的背景、干扰及其克服方法,讨论了水中Na、Mg、Ca等元素产生的基体效应对被测元素的影响。对含盐量较低的天然水样,可直接测定的痕量元素达50余种,测定限为0.x—xμg/L。高盐水样如海水、卤水等的测定,本文选择共沉淀法,以Fe(OH)_3为捕集剂,使被测元素与大量的碱金属、碱土金属基体分离。分离后可测40种痕量元素,测定限为0.0x—0.xμg/L。     

Trace Element Analysis of Fused Whole-Rock Glasses by Laser Ablation-ICP-MS and PIXE

The concentrations of fifty trace elements, including relatively volatile elements and transition metal elements, in fused glasses of Geological Survey of Japan rock reference materials GSJ JR-2, JA-1, JA-2, JB-1a, JB-3, JGb-1 and JF-1 were determined by particle (proton) induced X-ray emission (PIXE) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). The fused glasses were prepared by rapid fusion and subsequent quenching in welded platinum capsules and were found to be homogeneous for major elements and for trace elements with concentrations of more than 1 μg g^-1 within the observed precision (± 10% mean) on a 70 μm sampling scale. The values obtained by PIXE and LA-ICP-MS for the transition elements (Cr, Mn, Fe, Ni and Cu), the relatively volatile elements (Zn, Ga, Rb and Pb) and the refractory elements (Y, Zr, Nb and Th) with concentrations greater than a few μg g^-1 showed good agreement (within 10 % relative difference). The values for almost all the elements detected at concentrations higher than 1 μg g^-1 as determined by LA-ICP-MS also agreed well with the reference values (mean relative difference < ± 10%), except for B and Cu. The good agreement confirmed the appropriateness of the NIST SRM 600 series glass calibration reference material for LA-ICP-MS analysis of glasses with variable major-element compositions for almost all elements. The concentrations of Cu in all the samples were lower than the reference values, which was attributed to adsorption of the transition metals onto the platinum capsule during preparation.     

Laser Ablation ICP-MS Developments and Trends for 2003

This annual review of laser-ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS) covers the year 2003. Significant advances were made in understanding laser-sample interactions. In particular, research defined the distribution of particle sizes produced by the interplay of laser wavelength, laser pulse width and the gas environment of ablation. A link between particle sizes and elemental and isotopic fractionation at both the ablation site and in the ICP was established. Experimental 15 7 nm and femtosecond laser systems were tested with promising results. The number of applications of LA-ICP-MS in geology and environmental Earth science continued to grow with particular interest in element concentration and isotope ratio profiling of materials, linking composition to time scales. In situ isotopic ratio measurements were increasingly made using multicollector magnetic sector ICP-MS instruments. Other applications of wide interest included bulk sampling of rocks and ores prepared as lithium borate glasses; low level analysis of platinum-group elements, rhenium and gold in sulfides, metal and silicates; in situ uranium-lead zircon geochronology; and melt and fluid inclusion analysis.     

Determination of major and trace elements in sphalerite using laser ablation double focusing sector field ICP-MS

The analytical performance of laser ablation (LA) for the determination of Co, Fe, Cd, Ag, Mn, Cu and S in sphalerite was evaluated using double focusing sector field inductively coupled plasma mass spectrometry (ICP-SFMS). Samples were collected from Zinkgruvan, situated in the south central Sweden. The use of Zn for internal standardisation, together with correction for FeS impurities in sphalerite, allows straightforward quantification without using external methods for the determination of the actual Zn content. LA–ICP-SFMS results were compared with data obtained by conventional pneumatic nebulisation introduction of sample solutions following acid digestion. Good agreement between the two methods was obtained for homogeneously distributed elements. For the majority of the elements under consideration, LA–ICP-SFMS precision was better than 10% RSD.     

Platinum-Group Elements and Gold Determination in NiS Fire Assay Buttons by UV Laser Ablation ICP-MS

The direct analysis of nickel sulfide fire assay buttons by UV laser ablation ICP-MS was used to determine the platinum-group elements and gold in the following reference materials: UMT-1, WPR-1, WMG-1, GPt-4, GPt-6 and CHR-Bkg. The instrument was calibrated with buttons prepared using quartz doped with the appropriate standard solutions. Analytical precision (RSD) was generally better than 10%, although occasional higher RSDs may infer local heterogeneities within nickel sulfide buttons. Good or excellent agreement was observed between analysed and reference material values except Rh in UMT-1 and WMG-1, which suffered an interference from copper. Detection limits calculated as 10 s quantitation limits were Au (1.7 ng g⁻¹), Pd (3.3 ng g⁻¹), Pt (8.3 ng g⁻¹), Os (1.3 ng g⁻¹), Rh (1 ng g⁻¹), Ru (5 ng g⁻¹) and Ir (0.7 ng g⁻¹).     

Trace Element Determination of Single Fluid Inclusions in Quartz by Laser Ablation ICP-MS

Single fluid inclusions in quartz from a Pb-Zn-Ag carbonate replacement deposit were selected for trace element determination by laser ablation ICP-MS. Spikes in element intensities were noted between first breached fluids versus subsequent analyses, suggesting that accurate element concentrations may not be determined in smaller fluid inclusions when only one analysis is obtained before the fluid is exhausted. Elemental concentrations in the fluid inclusions were determined by external standardisation using solutions sealed in microcapillary tubes. Standards and single natural inclusion analyses give repeatabilities (%RSD) of ˜ 20% for Rb and Sr. Rubidium and strontium concentrations range from 0.56-5.07 μg ml^-1 and 1.12-27.4 μg ml^-1, respectively, whereas Zn and Ag are below detection limits (< 10 ng ml^-1). The results suggest that nearly all Zn and Ag are removed by the time hydrothermal fluids precipitate gangue minerals.     

Laser Ablation and Solution ICP-MS Determination of Rare Earth Elements in USGS BIR-1G, BHVO-2G and BCR-2G Glass Reference Materials

Data are reported for rare earth elements (REE) in three geological glass reference materials (BIR-1G, BHVO-2G and BCR-2G) using a UV (266 nm) laser ablation ICP-MS system and the classical (HF-HClO₄) acid decomposition method, followed by conventional nebulisation ICP-MS. External calibration of laser ablation analyses was performed using NIST SRM reference materials with internal standardisation using ²⁹Si and ⁴⁴Ca. Replicate analyses of reference basaltic glasses yielded an analytical precision of 1-5% (RSD) for all the elements by solution ICP-MS and 1-8% (RSD) by laser ablation ICP-MS. The relative differences between the REE concentrations measured by solution and laser ablation ICP-MS compared with the reference values were generally less than 11 % for most elements. The largest deviations occurred for La determined by solution ICP-MS in BIR-1G. The results of both solution and laser ablation ICP-MS agreed well, generally better than 7%, with the exception of La, Pr and Sm in BIR-1G. The measured REE laser ablation data for BIR-1G, BHVO-2G and BCR-2G agreed with the previously published data on these basaltic reference glasses, within a range of 0-10% for most elements. No significant influences were observed for the predicted spectral interferences on some REE isotopes in the analysis of basaltic glasses.     

激光剥蚀电感耦合等离子体质谱法测定碳酸盐矿物中元素组成

碳酸盐中微量元素信息可为探究古环境、古气候演化、壳幔相互作用以及成岩成矿等重要地质作用过程提供关键约束,其微量元素含量的准确测定一直备受学者关注。激光剥蚀电感耦合等离子体质谱（LA-ICP-MS）可提供碳酸盐矿物中微量元素含量的精细信息,而常规激光测试方法严重制约着碳酸盐矿物微量元素分析的空间分辨率和低含量元素的检测能力。相比于常规剥蚀池条件时的低频率分析,本研究通过采用气溶胶局部提取快速清洗剥蚀池结合高频率激光剥蚀的方式,快速提升激光微区分析瞬时信号强度,有效地提升峰形信号灵敏度（约13倍）,碳酸盐激光微区元素检出限降低5～10倍。在此激光分析模式下,分别采用纳秒和飞秒激光剥蚀联用四极杆等离子体质谱仪（LA-Q-ICP-MS）,以NIST610玻璃为外标,Ca为内标开展了较小激光剥蚀束斑（32μm）条件下碳酸盐矿物中微量元素（亲石元素、亲铁和亲硫元素）分析。结果表明,纳秒和飞秒激光分析碳酸盐矿物标样CGSP-A、CGSP-B、CGSP-C、CGSP-D和MACS-3获得的亲石元素（如Sc、Sr、Y、Ba、La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb和Th等）测试值与推荐值在误差范围内一致;而亲铁和亲硫元素（如Ni、Cu、Zn、As、Cd、Sn、Sb和Pb）测试结果则存在较大偏差（大于20%）,这可能与本研究选用的高频激光剥蚀和较小剥蚀束斑（32µm）造成显著的“Downhole”分馏效应有关。本研究通过研制新型激光剥蚀池,改变激光剥蚀方式,即采用气溶胶局部提取剥蚀池和高频率剥蚀方法可有效地提升碳酸盐矿物微量元素（如亲石元素）分析的空间分辨率和低含量元素检测能力,有利于促进碳酸盐矿物在地质环境等领域的广泛应用。     

Determination of Lithium, Beryllium and Boron at Trace Levels by Laser Ablation-Inductively Coupled Plasma-Sector Field Mass Spectrometry

The analytical capabilities of laser ablation (LA)-ICP-MS in determining Li, Be and B at trace levels in geological samples have been tested on a series of glass reference materials and natural samples. The LA-ICP-MS instrument used consisted of a sector-field ICP-MS coupled with a laser ablation microprobe operating at either 266 or 213 nm wavelength. Reference glasses from NIST (SRM 612, 614 and 616) and MPI-DING (KL2-G, ML3B-G, StHs6/80-G, GOR128-G, GOR132-G, T1-G and ATHO-G) were selected to develop the analytical method and to assess the best instrumental configuration. A series of calcic amphiboles with different Li, Be and B concentrations were also analysed using both LA-ICP-MS and SIMS to test the applicability of the method to natural minerals. Results indicated that with a spot size of 40 μm the agreement between measured and reference values of Li, Be and B is generally better than 10% for NIST SRM 612 and 20% for NIST SRM 614. Average reproducibility at the 2s level was 10% for Li, 20% for Be and 15% for B. Limits of detection were approximately 100 ng g^-1 for Be and B and 200 ng g^-1 for Li. These results were confirmed by analyses carried out on natural amphiboles and compared well in terms of precision and accuracy with those commonly achieved by SIMS.     

Accurate U-Pb Age and Trace Element Determinations of Zircon by Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry

Various zircons of Proterozoic to Oligocene ages (1060-31 Ma) were analysed by laser ablation-inductively coupled plasma-mass spectrometry. Calibration was performed using Harvard reference zircon 91500 or Australian National University reference zircon TEMORA 1 as external calibrant. The results agree with those obtained by SIMS within 2s error. Twenty-four trace and rare earth elements (P, Ti, Cr, Y, Nb, fourteen REE, Hf, Ta, Pb, Th and U) were analysed on four fragments of zircon 91500. NIST SRM 610 was used as the reference material and ²⁹Si was used as internal calibrant. Based on determinations of four fragments, this zircon shows significant intra-and inter-fragment variations in the range from 10% to 85% on a scale of 120 μm, with the variation of REE concentrations up to 38.7%, although the chondrite-normalised REE distributions are very similar. In contrast, the determined age values for zircon 91500 agree with TIMS data and are homogeneous within 8.7 Ma (2 s ). A two-stage ablation strategy was developed for optimising U-Pb age determinations with satisfactory trace element and REE results. The first cycle of ablation was used to collect data for age determination only, which was followed by continuous ablation on the same spot to determine REE and trace element concentrations. Based on this procedure, it was possible to measure zircon ages as low as 30.37 0.39 Ma (MSWD = 1.4; 2 s ). Other examples for older zircons are also given.     

Determination of REE, Y, Nb, Zr, Hf, Ta, Th and U in Geological Reference Materials LSHC-1 and Amf-1 by Solution and Laser Ablation ICP-MS

This paper presents data on REE and Y, Nb, Zr, Hf, Ta, Th and U abundances for two candidate reference materials (RMs), spinel lherzolite LSHC-1 and amphibole Amf-1, being currently developed at the Institute of Geochemistry SB RAS, Irkutsk. To determine the contents of these elements inductively coupled plasma-mass spectrometry was applied with: (i) solution nebulisation (solution ICP-MS) and (ii) laser ablation (LA-ICP-MS) of fused glass disks. The precision of results obtained by both techniques was better than 6% RSD for most elements. Accuracy was assessed by using the geochemical RMs JB-2, JGb-1 (GSJ) and MAG-1 (USGS). The trace element results by solution ICP-MS for JGb-1 and JB-2 agree with reference values presented by Imai et al. (1995, this Journal) within 1–10%. Significant differences were found for Nb and Ta determinations. The accuracy of LA-ICP-MS results evaluated by RM MAG-1 was within 4%, except for Eu (about 10%). The analytical results obtained for LSHC-1 and Amf-1 by solution ICP-MS and LA-ICP-MS were in good agreement with each other and with INAA and XRF data presented for the certification of these RMs. They can be considered as the indicative values for assigning certified values to the above-mentioned RMs.     

Comparison of UV and IR Laser Ablation ICP-MS on Silicate Reference Materials and Implementation of Normalisation Factors for Quantitative Measurements

Direct analysis of geological reference materials was performed by LA-ICP-MS using two Nd:YAG laser systems operating at 266 nm and 1064 nm. The aim of this work was to compare UV and IR laser ablation and to assess the potential of the technique for the quantitative bulk analysis of rocks, sediments and soils. The laser sampling process was investigated and the analytical performance of both systems was compared. The influence of the laser operating conditions and the nature of the matrix on ICP-MS response factors calculated for major, minor and trace elements was evaluated. Under consistent laser settings, the response factors appeared to be matrix dependent. For a given matrix, the response factors were also significantly different for the two lasers. Normalisation with a single matrix element was effective only for matrices with similar mineralogy. When operating at 266 nm instead of 1064 nm, matrix effects could be reduced but not overcome. However, variations of the response factors between the different matrices appeared to be similar within distinct groups of elements, reflecting geochemical associations. When using multiple internal standards, matrix effects but also effects of the laser wavelength, could be fully compensated.     

Preliminary Results from a New 157 nm Laser Ablation ICP-MS Instrument: New Opportunities in the Analysis of Solid Samples

Preliminary results are given from an excimer 157 nm laser ablation multiple-collector inductively coupled plasma-mass spectrometer (LA-MC-ICP-MS), used for the isotopic measurements of solid materials. Elements of geological interest with different volatilities such as Pb and U (e.g. zircon geochronology) and Cu and Zn (as examples of geochemical/biochemical tracers) were analysed. The range of ablation rates of 20-150 nm s^-1 enabled us to ablate the sample down to a depth of 45 μm for a 50 μm diameter pit. The Cu and Zn isotopic measurements gave values that were very stable with, on average, a 0.01 % standard error, comparable with that achieved in liquid mode measurements.     

Determination of Trace Elements in Twenty Six Chinese Geochemistry Reference Materials by Inductively Coupled Plasma-Mass Spectrometry

We report new data for thirty seven elements determined in twenty six Chinese geochemistry reference materials using inductively coupled plasma-mass spectrometry and a reliable and simple dissolution technique. One hundred milligrams of sample were digested with 1 ml of HF and 0.5 ml of HNO₃ in PTFE-lined stainless steel bombs heated to 200 °C for 12 hours. Insoluble residues were dissolved using 6 ml of 40% v/v HNO₃ heated to 140 C for 3 hours. Analytical calibration was accomplished using aqueous standard solutions. Rhodium was used as an internal standard to correct for matrix effects and instrument drift. Precisions were typically better than 5% RSD. Most of the data presented here agree well with the published certified values. For the elements Zr, Hf and most other trace elements, the measured values were less than 10% in error when compared to certified values.     

电感耦合等离子体质谱直接测定冰芯样品中痕量铅

利用电感耦合等离子体质谱仪对冰芯样品中超痕量Pb进行了直接测定。确定了测定溶液中浓度为ng/L级Pb的最佳仪器参数，载气流速、进样速度等与灵敏度之间的关系,浓度和扫描参数对分析精度的影响。仪器对Pb的质量浓度在20～100ng/L的分析精度(RSD，n=3)＜10%,标准加入回收率在85%～115%，检测下限为0.62ng/L，并给出了采自可可西里马兰冰川M3冰芯中Pb的分析结果。     

高空间分辨率LA-ICP-MS测定硅酸盐玻璃标准物质中42种微量元素

近年来,随着人们对关键金属（稀有金属、稀土金属、稀散金属和稀贵金属）的成矿机制、分布规律和绿色利用等研究日益加深,建立原位测定地质样品中关键金属元素（如REEs、Cr、Co、Ga、Ag、Cd、In、W、Tl等）分析方法对于研究关键金属元素的地球化学行为、分布规律和成矿机制具有重要意义。由于关键金属在地壳中丰度极低（一般为ng/g～μg/g级别）,赋存矿物非常细小（粒径μm级别）,因此需要建立高空间分辨率微区原位分析技术实现低含量（ng/g～μg/g）微量元素的定量。本文提出了高频剥蚀模式与Ar-N2等离子体技术相结合提升LA-ICP-MS对微量元素的检出能力,使之能够满足地质样品中关键金属元素的检测需求。结果表明：在Ar-N2等离子体条件下,采用高频（20Hz）剥蚀模式,LA-ICP-MS分析中大部分元素灵敏度提升了1.5～9倍。在使用高灵敏度X型截取锥时,高频剥蚀模式与氮气增敏技术相结合可以显著减小氧化物产率和降低U-Th分馏,获得更宽的载气流速区间（0.9～1.08L/min）以满足测试的仪器分析条件（ThO+/Th+＜0.5%和U/Th=1）。本研究开发的高空间分辨率LA-ICP-MS关键金属分析方法具有较低的检出限（在剥蚀束斑24μm条件下,30种元素的检出限＜0.02μg/g）,在高空间分辨率（10～24μm）条件下,通过对8种国际硅酸盐玻璃标准物质中42种微量元素进行定量分析,34种微量元素的测试结果的准确度优于10%,精密度优于15%,实现了在高空间分辨率条件下对微量元素的准确定量分析。