Development of an extended matrix-matched calibration protocol for fast, high-resolution, quantitative chemical mapping of major and trace elements of polymineralic samples by laser-ablation coupled to time-of-flight-mass-spectrometry (LA-ICP-TOF-MS) (original) (raw)
Related papers
Canadian Mineralogist, 2009
We demonstrate the application potential of laser-ablation -inductively coupled plasma -mass spectrometry (LA-ICP-MS) to map the distribution of major and trace elements in a variety of samples. The examples cover a wide range of elements, including the rare-earth elements (REE) and platinum-group elements (PGE). In order to test the capabilities of the technique, samples of different matrices were analyzed (i.e., carbonates, silicates and sulfides). The main obstacle to rapid processing of element-distribution maps by laser ablation was data processing. This has been overcome with the development of new software, and improved designs of the IoLITE, a laser ablation cell on commercially available laser systems. It is possible to obtain fully quantified concentration maps for single matrix samples using parallel adjoining line-scans. Single spot-analyses will result in better precision and accuracy, but the geochemical images are superior to conventional laser-ablation spot-analysis because they reveal geochemical details that are not visible under the microscope and cannot be appreciated with single-spot analyses. In addition to providing spatial information, individual line-scans that are used in the image acquisition offer the option to obtain quantitative results along any part of the scan. Using LA-ICP-MS imaging our dataset reveals zoned REE distribution in garnet crystals, heterogeneous occurrence of the PGE in sulfides, as well as the internal chemical structures in ooids with respect to conditions of growth. sommaIRE Nous démontrons ici le potentiel de l'analyse par ablation au laser avec plasma à couplage inductif et spectrometrie de masse (LA-ICP-MS) pour cartographier la distribution des éléments majeurs et en traces dans une variété d'échantillons. Ces exemples impliquent plusieurs éléments, y inclus les terres rares et les éléments du groupe du platine. Afin d'évaluer les capacités de la technique, nous avons choisi des échantillons ayant plusieurs matrices différentes (par exemple, carbonates, silicates et sulfides). L'obstacle principal à la production rapide de telles cartes de distribution par ablation au laser serait la réduction des données. La disponibilité d'un nouveau logiciel, IoLITE, et des affinements récents dans la conception de la cellule d'ablation sur les systèmes courants, ont permis de surmonter cet obstacle. Il est maintenant possible de construire des cartes de répartition d'éléments pleinenement quantifiées là où les échantillons ont une seule matrice en utilisant des balayages linéaires adjacents. Une analyse à un seul point peut produire une meilleure précision et justesse, mais les images géochimiques fournissent une outil supérieur à l'analyse conventionnelle en révélant des détails invisibles au microscope ou impossibles à obtenir avec une série d'analyses §
Techniques enabling in situ elemental and mineralogical analysis on extraterrestrial planets are strongly required for upcoming missions and are being continuously developed. There is ample need for quantitative and high-sensitivity analysis of elemental as well as isotopic composition of heterogeneous materials. Here we present in situ spatial and depth elemental profiles of a heterogeneous rock sample on a depth-scale of nanometres using a miniaturized laser ablation mass spectrometer (LMS) designed for planetary space missions. We show that the LMS spectra alone could provide highly detailed compositional, three-dimensional information and oxidation properties of a natural, heterogeneous rock sample. We also show that a combination of the LMS and Raman spectroscopy provide comprehensive mineralogical details of the investigated sample. These findings are of great importance for future space missions where quick, in situ determination of the mineralogy could play a role in the process of selecting a suitable spot for drilling.
Microanalysis of minerals by an Excimer UV-LA-ICP-MS system
Chemical Geology, 1996
This paper is a performance evaluation of a prototype laser-ablation microanalytical system composed of an UV Excimer laser and a high-sensitivity inductively coupled plasma mass spectrometer (XLA-ICP-MS). The laser was optimized for trace-element microanalysis of silicate minerals, and the effects of different parameters (laser power, focus, carder gas flow, etc.) on the performance characteristics were studied. The crater size and shape produced by the XLA system were compared to a solid state IR LA system (Nd:YAG) and proved to be superior. Crater sizes achievable in thin sections vary from 1000 to 10 Ixm, although the best analytical results for this prototype were achieved at crater diameters of ~ 40-60 I~m and depths of ~ 30-40 p,m. Detection limits vary from ~ 1 ppb for 1000-1xm craters to ~ 1000 ppb for 10-1~m craters. The precision obtained for the measurements depends on both crater size and concentration in the ablated mineral. Typical RSD for five replicate analyses of the above-mentioned minerals were +4% and ___ 10% for concentrations > 10 and 1-10 ppm, respectively. Comparison of XLA with solution nebulization analysis shows an excellent agreement for most elements. The XLA source, in contrast with other laser sources currently available, produced no noticeable chemical fractionation during ablation for all elements except radiogenic 2°Tpb and, to a lesser extent, 2°6pb. This effect is a serious limitation for using LA-ICP-MS for in situ lead geochronology.
High-resolution LA-ICP-MS trace element mapping of igneous minerals: In search of magma histories
We report experiments on optimisation of LA-ICP-MS mapping as a tool for visualising and quantifying internal structure of trace element concentration in igneous minerals. The experimental design was refined with maps on clinopyroxene and amphibole macrocrysts (mainly antecrysts) from a porphyritic lamprophyre in NE Spain, as well as on a high precision metal wire grid. In terms of spatial resolution, we demonstrate with scanning electron microscope and white light interferometry that a full ablation removes between 0.4 and 0.7 μm of material, depending on ablation parameters. Maps were produced with square laser beam spots of 12 and 24 μm. It was found that complexities can be resolved in the sample even though they are smaller than the beam diameter (e.g., 7–10 μm discontinuities using 12 μm laser beam). Resolution in x and y was found to be identical, probably reflecting the fast washout of the two-volume ablation cell and the short total dwell time of the analyte menu selected. Due to the excellent stage reproducibility and the limited ablation depth, it is feasible to re-ablate the identical map area many times employing different instrument parameters or analyte menus. On the magmatic crystals, LA-ICP-MS maps define very sharp compositional zoning in trace elements, highlighting complex crystallisation histories where 'normal' magmatic fractionation is not the only process. Events of mafic recharge are easily recognised as zones enriched in compatible metals such as Cr, Ni or Sc. Further, trace element maps reveal complexities in mineral zoning previously undetectable with petrography or major element data. These include resorbed primitive cores and oscillatory zoning within apparently homogeneous mineral zones. Therefore, LA-ICP-MS mapping opens a new window of opportunity for analysis of magmatic histories. The wide combination of instrumental parameters, such as laser beam size, scan speed and repetition rate, make it possible to carry out experiments at different levels of detail. We recommend a two-step approach to mapping. The initial step involves rapid maps to gain an overview of potential complexities in the sample; this enhances representativeness of the analysed materials, as a large number of crystals and trace elements can be tested in little time. Subsequently, detailed maps can be carried out on areas of interest. An additional function-ality is to create 1D-profiles from 2D-maps. The potential of the technique to unveil compositional complexities efficiently and at greater detail than traditional microanalysis will help to improve our understanding of processes in the magmatic environment and beyond.
American Journal of Analytical Chemistry, 2014
The laser ablation technique, coupled with the use of quadrupole ICPMS equipment, proved a powerful tool for determination of trace elements in minerals. At the University of São Paulo, the technique was implemented for the study of minerals such as olivines, pyroxenes and biotites. The main problem to be tackled is the availability of proper multi-element reference materials usually prepared synthetically as glasses with various compositions by NIST and fused rock glasses by the Max Planck Institute (MPI) and USGS (basalts, andesite, quartz diorite, komatiites). The best tested ones are the NIST glasses, with good homogeneity and reliable compositional data for over 40 elements. Results are here presented that test additional RM's. NIST 612 and 610 were used for calibration purposes. The best results were obtained for rock glasses USGS basalts BHVO-2G, BIR-1G and BCR-2G (better homogeneity and recommended values). Our contribution tests especially the MPI komatiites glasses GOR-128 and GOR-132G, basalts KL-2G and ML-3BG, andesite StHs-6/ 80G and quartz diorite T-1G, discussing homogeneity issues and providing new data. There is a need for additional preparation of reliable reference materials.
Here we present an approach to laser ablation ICP-MS mapping of multiphase assemblages that permits the use of different internal standard elements, concentration values and reference materials for each mineral. In this way we obtain not only broad pictures of elemental distributions within samples but can also extract high accuracy concentration data for any user-selected region. This is accomplished by assigning regions of an image to corresponding mineral phases on a pixel-by-pixel basis. In this way, accurate trace element concentrations can be determined for each mineral phase, despite potential variations in their ablation characteristics. We present an example where elemental maps are constructed from ablation of a gabbroic sample that includes the phases apatite, amphibole and plagioclase.
Geostandards and Geoanalytical Research, 2018
Laser ablation inductively coupled plasma time-of-flight mass spectrometry (LA-ICP-ToF-MS) was used to generate quantitative elemental images of a mineralogically and texturally complex fault rock of the Northern Apennines of Italy (Zuccale Fault, eastern Island of Elba). Using LA-ICP-ToF-MS combined with a low-dispersion LA cell, we were able to generate large format (4 mm 3 2 mm), high-resolution (5 lm), high dynamic range (1-10 6 lg g-1) and quantitative multi-elemental two-dimensional compositional maps within a data acquisition time of a few hours. To quantify element mass fractions across the heterogeneous sample of the Zuccale Fault, we used a 100% species-mass normalisation approach that took into account different mineral phases across the specimen. To assign mineral phase directly from LA-ICP-ToF-MS data, we exploited the segregation of sulfur and calcium between distinct phases to threshold element images and develop mineral-phase-specific masks. Moreover, we demonstrate agreement between elemental mass fractions determined by LA-ICP-ToF-MS imaging with 100% normalisation quantification and conventional LA-ICP-MS analysis with internal standard element-based quantification. Finally, we discuss how this elemental imaging provides unique insights into the genesis of the Zuccale Fault.
Advances in ICP-MS technology and the application of multi-element geochemistry to exploration
Geochemistry: Exploration, Environment, Analysis, 2019
There have been several advances in inductively coupled plasma mass spectrometer (ICP-MS) analytical technologies in the last decade (2007 to 2017). Collision/reaction cell ICP-MS and triple quadrupole ICP-MS instruments can produce lower detection limits for select elements that experience interferences with a standard quadrupole instrument (i.e., Se and As). Triple quadrupole ICP-MS instruments in particular, can eliminate virtually all polyatomic or isobaric interferences for highly accurate measurements of some element isotopes systematics that are of great interest in mineral exploration, namely Pb/Pb. Laser ablation ICP-MS has become more popular as an effective analytical tool to measure mineral grain trace elements, which could assist in vectoring to mineralization or exploration drill targets. The ablation of a spot on a Li-borate fused glass disk paired with X-Ray fluorescence (XRF) analysis has also gained popularity as an alternative to total whole rock characterization packages that employ several separate digestions and analytical methods. While there have been several advancements in ICP-MS technologies in exploration geochemistry in the last decade, they have not been widely accepted or implemented. This slow adaptation could be due to the extended recession in the mining industry over the last 5 years, which is not currently over. It is also possible that standard ICP-MS data (i.e., no collision/reaction cell) is still fit for purpose. This stands in stark contrast to implementation of ICP-MS in the previous decade (1997 to 2007), which was transformational for the industry. Consideration of all elements from large multi-element ICP-MS analytical suites for mineral exploration can be an extremely powerful tool in the exploration toolkit. The discovery of the White Gold district, Yukon, is a prime example of how the utilization of soil geochemical data, when plotted spatially, can vector to Au mineralization. The presence of Au+As+Sb soil anomalies were key to delineating mineralization, especially when accompanied by publicly available geological, geographical, and geophysical data. Additionally, elements and element ratios not typically considered in Au exploration including Ni and U were utilized to determine the lithological and structural controls on mineralization. The availability of multi-element ICP-MS data was also useful in the discovery of the Cascadero Copper Taron Cesium deposit. Ore grade Cs was discovered only because Cs was included in the multi-element ICP-MS exploration geochemistry suite. Before the availability of ICP-MS, it is unlikely that this deposit would have been discovered.
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1997
A brief overview is provided of the uses of AMS in mineral analysis, emphasizing the selection of appropriate samples. Simple guidelines are given for judging the suitability of a set of samples (and the type of problem that they pose) for AMS, as opposed to other methods of in-situ analysis. Optimal interpretation of the AMS data requires that the method be employed in conjunction with a range of other types of information. These include textural and mineralogical observations obtained with petrographic or scanning electron microscopes, plus in-situ chemical data for areas of the target typically l-250 pm in diameter, obtained by some combination of complementary techniques, such as electron, proton or ion microprobe analysis (EPM, PIXE and SIMS, respectively).
LA-ICP-MS is one of the most promising techniques for in situ analysis of geological and environmental samples. However, there are some limitations with respect to measurement accuracy, in particular for volatile and siderophile/chalcophile elements, when using non-matrix-matched calibration. We therefore investigated matrix-related effects with a new 200 nm femtosecond (fs) laser ablation system (NWRFemto200) using reference materials with different matrices and spot sizes from 10 to 55 lm. We also performed similar experiments with two nanosecond (ns) lasers, a 193 nm excimer (ESI NWR 193) and a 213 nm Nd:YAG (NWR UP-213) laser. The ion intensity of the 200 nm fs laser ablation was much lower than that of the 213 nm Nd: YAG laser, because the ablation rate was a factor of about 30 lower. Our experiments did not show significant matrix dependency with the 200 nm fs laser. Therefore, a non-matrix-matched calibration for the multi-element analysis of quite different matrices could be performed. This is demonstrated with analytical results from twenty-two international synthetic silicate glass, geological glass, mineral, phosphate and carbonate reference materials. Calibration was performed with the certified NIST SRM 610 glass, exclusively. Within overall analytical uncertainties, the 200 nm fs LA-ICP-MS data agreed with available reference values. Synthesis and preliminary characterisation of new silicate, phosphate and titanite reference glasses. Geostandards and Geoanalytical Research, 32, 39-54.