Department of Earth Sciences - LA-ICP-MS

LA-ICP-MS

The Department of Earth Sciences at University of Manitoba operates a Thermo Finnigan Element 2 High Resolution-Inductively Coupled Plasma-Mass Spectrometry (HR-ICP-MS). The HR-ICP-MS is used in combination with a New Wave Research UP-213 nanosecond laser ablation system and a Quantronix Integra-C femtosecond laser ablation system for solid sample micro-analyses. In addition, a CETAC ASX-500 autosampler allows for automated liquid sample analyses.

Our instrument setup with Thermo Finnigan Element 2 HR-ICP-MS and  New Wave UP-213 nanosecond laser ablation system (left) and Quantronix Integra-C femtosecond laser ablation system (right)

LA-ICP-MS principles

A laser ablation system allow micro-local analysis of various solid samples when it is coupled to ICP-MS. A laser beam (213 nm nanosecond or 785 nm or 266 nm femtosecond in our laboratory) is focused on the target samples, and turns it into aerosols. Laser beam size, energy and repetition rates are optimized for best signal intensity and stability. A computer programmable sample stage allow laser ablations to be done in spots, lines, and 2D map. The aerosols are carried to Ar plasma by a stream of He. The mixture of sample and Ar plasma is introduced into the mass spectrometer through sampler and skimmer cones. Ions are separated according to their mass/charge ratios by the electromagnetic forces. If necessary, spectral interferences can be removed by increasing mass resolving power.

SN-ICP-MS principles

In solution nebulization ICP-MS, solution samples are pumped to a nebulizer by a peristaltic pump. In spray chamber, it is mixed with argon and then introduced to  the torch for ionization. Sample introduction can be automated by the autosampler.

Data reduction

For both LA-ICP-MS and SN-ICP-MS, the following steps are required to quantify the results:

• To relate measured ion intensities (cps) to concentrations, calibration must be done using standard reference materials with the matrix similar to that of the    samples. Standards can consist of a series of solutions spiked with known amounts of elements, solutions of standard reference materials with known amount of trace elements (e.g., NIST SRM 1640), and, for LA-ICP-MS, artificial glass doped with known amounts of trace elements (e.g., NIST SRM 610), or fuesed natural rock materials (e.g., USGS BCR-2G).
• For each standard and sample analyzed, at least one element of known concentration must be analyzed to correct for variations in sample introduction rates (e.g., solution uptake rates by the peristaltic pump and laser ablation yield differences). For SN-ICP-MS, typically single-element (e.g., In or Bi) spike solution is added to the sample and standard solutions. In LA-ICP-MS, one of major elements in the sample previously been determined by electron microprobe is used as an internal standard because internal spiking is not possible.
• To evaluate limits of detection, a laboratory blank must be added within the analytical session. The blank must be chemically processed exactly the same way as the samples so that possible contamination from the solvents or containers can be quantified. In LA-ICP-MS, gas blank levels are measured before firing the laser.
• To characterize accuracy in both LA-ICP-MS and SN-ICP-MS, at least one standards should be periodically analyzed as an unknown throughout an analytical session.
• For LA-ICP-MS, GLITTER and Iolite are available for computer assisted data reduction.

Selected applications of LA-ICP-MS and SN-ICP-MS

Because of versatile sample introduction methods, superior detectability, and isotopic capability, LA-ICP-MS and SN-ICP-MS found wide range of applications in geological, biological, environmental, and industrial fields. The following is a selected list of materials that can be analyzed by LA-ICP-MS and SN-ICP-MS:

• Geological applications: rocks, mineral, meteorite, U-Pb geochronology, Sr isotope ratios, and trace element geothermometers
• Animal science applications:  fish otoliths, bones, claws, feathers, hair, nails, shells, teeth, tissues, urine, and isotopic tracing.
• Plant science applications: barks, tree rings, leaves and roots.
• Environmental applications: atmospheric deposits, snow, ice, waters, and sludge.
• Industrial applications: alloys, ceramics, glass, plastic, steel, and semiconductors.

Sample Preparation

Sample preparation is responsibility of the user. Please consult with the lab manager for any special sample preparation required for specific types of samples, or specific standards that may be needed.

SN-ICP-MS sample preparation

It is preferred that the user provides standard solutions spanning the range of concentrations of elements of interest and that the samples and standards are spiked with a precisely known amount of spike solution of elements to be used as internal standards. If standards are not provided, samples are not spiked, and/or concentration ranges are not known, additional sample preparation charges may apply (see Fee_Schedules). The following are for typical external calibration method and if standard addition technique is required, please consult the lab manager.

• The solutions must be free of solid particulates larger than 0.2 µm and organic compounds.
• A minimum of 10 mL should be submitted for each sample.
• The solutions to be run in the ICP-MS should be 1% - 2% HNO3.
• Reagents used for the sample preparation should be double distilled or ultrapure to ensure low background levels.
• Total dissolved solids (sample weight/solution volume) of solutions should be less than 0.1%.
• Blank solution: The user should provide a blank. This blank should be prepared by the same way as the unknowns.
• Standards: The user should provide a set of at least 4 standards (a minimum of 20 mL) for each run that have concentration range similar to that expected from the unknowns. These standards will be used to generate the calibration curves from which the concentrations of trace elements in the unknown samples will be estimated. For best results, the standards should have a similar matrix to the unknowns and be prepared by the same method. 
• Internal standards: The concentration of a internal standard should be the same in blank, standards, and samples. The internal standard should not have isobaric interferences with the analytes. The samples and standard reference materials should have negligible concentrations of the internal standard. When analyzing a group of elements with a wide range of masses, several internal standards should be used with a similarly wide range of masses (e.g. Be, In and Bi).

LA-ICP-MS sample preparation

• Samples can be prepared as 1 inch diameter round epoxy mounts or petrographic size (1 inch by 1 ¾ inch) slide glass.
• Laser mounts should be polished, cleaned, free of coatings, and > 30 microns thick.

 Fee Schedules

The following schedules show estimated fees and may be subject to change depending on actual project costs. LA-ICP-MS refers to both nanosecond and femtosecond laser ablation ICP-MS. SN-ICP-MS refers to solution nebulization ICP-MS. Client will be billed one hour each day for optimizing the instruments. Discounts (up to 15%) may be given for method development and large sample runs. Contact lab manager for more information.

Fee schedules as of November 2019

Fee Schedules

LA-ICPMS refers to laser ablation ICPMS for which samples are prepared as solid forms. SN-ICPMS refers to solution nebulization ICP-MS for which samples are introduced to the ICPMS as solution. Discounts may be given for method development and large sample runs. Contact lab manager for more information.

Fee schedules as of November 2019

Fee/hour

Hourly rates in parenthesis are for LA-ICPMS work done by the lab manager. One hour for optimizing the instrument will be charged each day.

Fee/otolith

Line profiles are from rim to rim through core. Scanning speed can vary from 2 µm/s to 10 µm/s depending on the size of otoliths. Data reduction is included.

Sample preparation fee/otolith

Solution sample preparation fee

Data reduction fee (% of total cost)

Contact

Panseok Yang
Department of Geological Sciences
University of Manitoba
125 Dysart Road, Room 334 Wallace Bldg
Winnipeg, MB R3T 2N2

Phone: (204) 474-7465
Fax: (204) 474-7623
Email: Panseok.Yang@umanitoba.ca