Laser-ablation system for LA-ICP-MS (Teledyne-Photon Machines Analyte G2)

Description

The laser ablation system is a micro-sample introduction device used in tandem with ICP-MS, here, the Element 2 sector field ICP-MS, for major and trace element analyses of solids and glasses. On our system, a 193 nm UV laser beam is generated by an ArF excimer gas, for optimal and consistent performance across materials. The ablation system is equipped of a transmitted and reflected light optical microscopy camera, which helps the user navigate their samples and program their ablations ahead of analysis. Once the sample ablation sequence is set, the laser will remotely control the ICP-MS, syncing data acquisition with ablations.

Below are the general sample requirements, if your samples do not meet these requirements, please contact us.

Thin sections: Polished sections are preferred for best pre-ablation sample observations, but working with unpolished sections will not alter the quality of the ablation. Regular petrographic thin sections (30 mm) are acceptable but their thinness may limit the ablation duration and impact data quality. Thicker sections are preferred. Surface scans as line or raster are also possible as an alternative to spots and yield better results on homogeneous samples. Ablation spot size can vary from 110 μm diameter to 5 μm, but signal intensity is directly proportional to the sample area, and data quality and detection limits will substantially degrade for small sample sizes. 30 μm or larger are generally preferred.

Grain mounts in epoxy: 1 inch mounts or 1 cm must be thinner than 1.5 cm to fit on the sample tray. As with thin sections, the better the polishing, the better the imaging for the user. The microscope’s reflected light capability allows for thick and opaque polished samples to be examined carefully before ablation.

Custom sizes may be accepted if they can be mounted on our sample tray, with minimum and maximum sizes requirements.

*Picture of our sample tray, filled with 4 thin sections and multiple standards in the circular holders.*

Pictures of a micro-crystalline assemblage of plagioclase feldspar, pyroxene and oxide in a volcanic glass matrix, as seen with the laser microscope during preparation for ablation. The polarized transmitted light mode (left), reflected light mode (center) and combined mode (right) each highlight different materials and help the user locate the best surfaces for ablation (such as the pyroxene micro-crystal under the 40 mm target) and avoid surface contamination, such as the circular artefact on the upper right corner of the reflected light image.

The two-volume sample cell is fluxed with high purity helium, and the ablated material is conveyed to the ICP-MS in the helium flux, where it is mixed with argon and ionized as plasma before elemental analysis.

As with solution mode ICP-MS, the user can select as many elements as they need for analysis by ICP-MS.

We provide calibration standards comprising the best-characterized reference materials for LA-ICP-MS (silicate glasses, synthetic and natural), and also welcome users’ own standard reference materials, especially for matrices for which no broadly available standards exist.

All major and trace element analyses are run against calibration standards (external calibration method), analyses of standards run as unknown (secondary standards) are also provided. Blanks are subtracted to each analysis and, whenever possible, we perform a pre-ablation to eliminate potential surface contamination of the samples. See example of a LA-ICP-MS signal below.

Example of Data

Example of a time-integrated ablation signal (“chromatogram”) of ²⁰⁸Pb in a reference material (NIST SRM 612), obtained as part of a multi-elemental analysis, intensities expressed in counts per second). NIST SRM 612 contains ~38 ppm Pb, with a natural isotopic abundance ratio.

Contact and Pricing

We offer bulk analyses of powdered samples, which we charge per sample using slightly higher rates than we do for solution work by ICP-MS, to reflect lower sample throughput and higher instrumentation use.

Bulk sample analysis, LA-ICP-MS, Cost Per Sample (USD$)
Description	NIU	Academic	Commercial
Instrument use*	$30-100	$40-120	$60-200
Technician time**	N/A	N/A	$100
Minimum fee for new project***	$300

For all other projects, charges are assessed per hour of instrument use. Users should discuss their projects for an estimate of time required. The most time-consuming part of LA-ICP-MS often involves setting up ablations on the samples, and is to be budgeted in instrument use time. It is preferred that users set up their own ablations (first assisted with technician, or autonomously after adequate training). Reduced hourly rates will be offered to trained academics and students using the instrumentation system on their own.

Other analysis types, LA-ICP-MS, Cost Per Hour (USD$)
Description	NIU	Academic	Commercial
Instrument use*	$80	$100	$160
Technician time**	N/A	N/A	$100
Minimum fee for new project***	$300

** Technician time is charged for projects which need extra sample processing time due to improper preparation, or for samples of unknown composition that may require a preliminary qualitative analysis.

*** To reflect the low sample throughput and method development inherent to projects that are new to us, a flat-rate of $300 is charged in lieu of the hourly fees, should these amount <$300. Returning customers repeating an existing method on additional samples will be charged the hourly rate.

Contact Guillaume Girard at ggirard@niu.edu for inquiries and questions.

Research

Contact Us

Micro-Compositional Analysis Laboratory

Guillaume Girard
Research Associate
ggirard@niu.edu

Joshua Schwartz
Laboratory Manager
joshua.schwartz@niu.edu
815-753-7930