Laser ablation ICP-MS allows for highly sensitive elemental and isotopic analysis to be performed directly on solid samples (e.g., in-situ analysis of minerals and glass, fused powders etc.).
The major advantages of LA-ICP-MS are that analyses with the limit of detection approaching ppb (parts per billion)-level can be performed without extensive sample preparation. The technique provides time-resolved analytical data as a depth profile into the sample, and individual analyses can be acquired in seconds, making LA-ICP-MS one of the fastest microanalytical techniques. Finally, analysis involves very small sample sizes (picograms to femtograms), which is especially useful for valuable or limited samples.
The LA-ICP-MS facilities at PCIGR are available to academic/NSERC, government and industry research sectors at hourly rates. We aim to provide training to users so that they can acquire their own data; however, for cases where this is not possible, analysis can be performed on a contractual basis by our trained research staff.
The RESOlution M-50-LR (Applied Spectra, Inc.) is a Class I laser device equipped with a UV excimer laser source (Coherent COMPex Pro 110, 193nm). The two-volume cell (Laurin Technic Pty) can accommodate a number of samples of various dimensions (e.g., microscopic slides, mineral mounts, thick rock sections, slides of speleotherms, drill cores and samples of irregular shape).
At PCIGR, the laser system can be connected to either (or both) the Agilent 7700x quadrupole ICP-MS and/or the Nu AttoM HR-SF-ICP-MS, according to measurement requirements. Fast, robust trace element analyses are performed on the Agilent while low-level trace elements and isotope ratio analyses are carried out by the NuAttom. Both methods are combined (i.e., split-stream LA-ICP-MS) to achieve simultaneous trace element and isotope ratio analyses.
Analytical runs are easily set up and run automatically, even for 24/7 runs (e.g., for imaging) and delicate sample selections. With the laser software, users are able to navigate through samples due to the automated image stitching, and perform runs of either individual manually selected points or rasters/lines.
To obtain quantitative data from time-resolved data, the concentration of an internal reference element (e.g., Ca, Si) must be previously determined. This is commonly measured by electron microprobe or X-ray fluorescence. The concentration of a standard having a similar matrix must also be known. We provide a variety of certified reference materials (e.g., NIST glasses, USGS basalts) to ensure proper matrix-matching.
PCIGR offers a workstation (LaserSpot) designed for preparation, imaging and data processing of in-situ and micro-analysis. For data processing, we provide access to the Iolite software package that enables graphical visualization of time-resolved data. Iolite allows for the selection of integrations from the raw data, correction of background signals, selection of integration intervals for reference materials and unknowns, and finally, data reduction calculations to determine concentrations/isotopic ratios and analytical uncertainties.
Analytical Precision and Accuracy
At PCIGR, the LA-ICP-MS setup is used for a variety of applications, including (though not limited to) trace element analysis of a large suite of chemical elements in minerals, glasses, and other materials (e.g., otoliths, teeth), U-Pb geochronology to date zircon and other common accessory minerals, and radiogenic isotope analysis.
Recently, we have focused on the measurement of high-precision Pb isotope ratios in plagioclase, clinopyroxene, and sulphide minerals in solid samples on the Nu AttoM HR-SF-ICP-MS, either measuring the isotope ratios alone (Fourny et al., 2020), or together with trace element concentrations (Agilent quadrupole ICP-MS) using a split-stream method (Cho, 2019; MSc thesis). The following plots summarize the analytical results of selected standards measured in each study.