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ICP-MS Laboratory

Contact: Matt Parsons
Department of Geological Sciences
206 Natural Sciences Building
Michigan State University, East Lansing, MI 48824-1115

Phone: (517)355-9303 / (517)884-2015  
Fax: (517) 353-8787

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Applications
Fees
Sample Preparation and Standards
Sample introduction Systems

The Department of Geological Sciences operates a Micromass (now part of Thermo Fisher Scientific, Inc.) Platform Inductively Coupled Plasma-Mass Spectrometer (ICP-MS). The Platform has a hexapole collision cell, which minimizes interferences caused by argon molecules (e.g. 40Ar 35Cl+ on 75As+). The Platform ICP-MS is capable of analyzing 74 elements, either as single elements or in multi-element analysis, with high precision and sensitivity. The analyses can be qualitative or quantitative.

The Platform ICP-MS is located in the Food Safety and Toxicology building on the MSU campus in a clean laboratory. The clean environment of the room complements the high sensitivity of the instrument in being able to analyze low level concentrations (ppt).

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Applications of ICP-MS

ICP-MS instruments are becoming common in analytical laboratories because of their versatility. In a few minutes, the ICP-MS can produce high quality data for elements with wide range of atomic masses, from 6Li to 238U. The best results are obtained for elements that have ionization potentials lower than those of the carrying gas (Ar, 15.8 eV) and that are free of isobaric interferences. The most common applications for ICP-MS are in biological, environmental, geological, and industrial fields. The following is a modest list of materials that have been analyzed by ICP-MS.

Archeological Applications: artifacts (e.g. ancient ceramics, bronze mirrors) and raw materials

Biological Applications: Animals: blood, bones, feathers, feces, hair, human breath, milk, red cells, serum, shells, stomach contents, teeth, tissues, urine, zooplankton.  Plants: barks, broccoli, fertilizers, fruits, garlic, grass, leaves, mushrooms, roots, tobacco, tea, tree rings, wood.  Foods: beverages, food packaging, juices, milk, metabolites, rice flour, sea food, wine.
Health sciences: chemotherapy drugs, illicit drugs, medicines, toxicology studies, metabolism studies, dietary supplements.

Earth Science Applications: fossils, minerals, meteorites, rocks, soil, waters.

Environmental Applications: atmospheric deposits (wet, dry), brines, car exhaust particles, coal fly ash, dust, gases from landfills, incinerator wastes, organic waste, oil pollution, paint, snow, sludge, washing powders.

Forensic Science: glass, illicit drugs and plants, soils, paint, metals.

Industrial Applications: alloys, automobile catalytic converters, ceramics, dyes, glass, lab gloves, nuclear industry products, paint, paper, petroleum based products, plastic, rare earth element compounds, steel, silica, superconductors, sulfides.

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Analytical Fees

The joint X-ray Fluorescence and ICP-MS Laboratories at MSU offer a variety of analytical services, including elemental packages for rock and soil samples (Option 1 below).

The following schedule shows estimated fees.  Additional discounts may be given for large numbers of samples or in-house sample preparation.  Fees are subject to change at any time.  Prices reflect a normal turn-around time of about one (1) month.  Rush orders may require additional charges.  Please consult Matt Parsons (Matt Parsons) before officially quoting any prices.

1. Geological (rock and soil) Samples

Sample Preparation: All samples are analyzed as glass disks, prepared by fusion of finely-ground rock powders with lithium tetraborate.  Samples may be submitted as powders or in bulk.  Submit a minimum of 8 grams powder or 30 grams whole rock.  Sample preparation fees for any type of elemental analysis are as follows:

Trimming/powdering of bulk samples	$5/sample
Li2B4O7 fusion (of powdered samples*)	$6.50/sample

*Submitted sample powders should be fine enough so they are not “gritty” when rubbed between sheets of paper.  Re-powdering of gritty samples will require an additional charge.

Users may also request to prepare their own samples at MSU, subject to a $2.00/sample materials charge.

Major and Trace Element Packages (per sample):

	Academic Research	Commercial
Major elements only (XRF)	$20	$40
Major elements + Rb, Sr, and Zr	$27	$54
Major elements + 11 trace elements (XRF)	$40	$80
Major elements + 29 trace elements (XRF + LA-ICP-MS)*	$50	$100

*A minimum charge of $250 (academic) and $500 (commercial) will apply for all geological analyses involving LA-ICP-MS.  This cost reflects the minimum time to tune the instrument, run standards, and data processing.

2. ICP-MS (solution) Samples

Samples must be free of solids and organic compounds, and in a matrix of 1-2% HNO3.  A minimum of 10 mL should be submitted for each sample.  Standard solutions spanning the range of concentrations of elements of interest must be provided.  If standards are not provided and/or concentrations are known, additional sample preparation charges will apply (see below):

	Self-operator	Academic Research	Commercial
ICP-MS cost per hour	$75	$100	$200
Additional standard preparation or screening, per hour, one (1) hour minimum	n/a	$150	$300

NOTE: All self-operator rates apply to users that prepare samples and standards at MSU and have sufficient training to set-up/run samples using the auto-sampler, manual sample introduction or laser ablation equipment.  Training is provided for users that will use the instruments regularly over a longer period of time (typically 6-12 months or longer).

3. LA-ICP-MS Samples

Based on the relative complexity of analyses (number of ablations, standardization, data processing, etc.) rates will vary for solid sample introduction.  The following rates are estimates only.  Please contact the lab manager for further pricing.  The minimum fee reflects protocol development and data processing.

	Self-operator	Academic Research	Commercial
LA-ICP-MS cost per hour	$100	$125	$250
LA-ICP-MS minimum charge	n/a	$250	$500

 

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Sample Preparation and Standards

The Platform ICP-MS is equipped with a variety of sample introduction systems that allow the analyses of solid, aqueous and gas samples.  The most common means of sample introduction are pneumatic nebulization of aqueous liquids via a concentric nebulizer and laser ablation of solid samples.

Reagents used for the sample preparation should be double distilled or ultra pure. The high purity acids reduce contamination and background levels in the instrument.  Total dissolved solids of solutions should be less than 0.1% (the total dissolved solids is the ratio of the sample weight to the solution volume).  The solutions to be run in the ICP-MS should be 1% - 2% HNO3.

Sample preparation is responsibility of the user.  Always discuss the sample preparation procedure with the lab manager to make sure that the procedure is compatible with the ICP-MS.

SOLUTION SAMPLE PREPARATION

1. Standards

There are two types of standards that are used in solution ICP-MS. One set of standards includes those solutions prepared from single or multi-element standards that are commercially produced. The second set of standards is known as SRM (standard reference material).  SRMs are samples with well-defined compositions (working values) from analyses by many different laboratories.

The user should provide a set of at least 4 standards 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 composition of the unknown samples will be inferred. The user should discuss the number and type of standards most appropriate for the analysis with the Lab Manager.

For best results, the standards should have a similar matrix to the unknowns and prepared by the same method.  If samples and standards are not matrix-matched, the accuracy of results may be compromised.

If the composition of the sample is completely unknown, a qualitative scan must be run prior to the preparation of the standards.

2. Blank solution

The user should provide a procedural blank. This blank should be prepared by the same method used to prepare the unknowns. If the unknowns have not been processed by any digestion method, the blank would be diluted acid of similar characteristics to those of the unknowns. The procedure blank will be the first solution to be run to check the cleanness of the sample preparation procedure. If the blank produces unacceptably high counts, the analyses will not proceed. To avoid wasting samples, use only high purity reagents in all the stages of sample preparation. We need to keep the Platform ICP-MS as clean as possible to be able to reach low levels of detection (ppt-ppq).

3. Calibration

Common calibration strategies for ICP-MS analyses are internal standards, external standard calibration, standard additions, or isotope dilution.

3.1. Internal standards
Internal standards (IS) are elements that are added to the blank, standards, and samples in known concentrations. The concentration of a given internal standard should be the same in all the solutions (i.e. blank, standards, and samples).

Internal standards are widely used in ICP-MS analyses to correct for variations in the instrument response as the analysis proceeds (drift) and to calculate the analyte concentrations of the samples.

To select an internal standard keep in mind the following:
a. the internal standard should not have isobaric interferences with the analyte(s);
b. the samples and standard reference materials should have negligible concentrations of the IS;
c. 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. In and Bi).

3.2. External calibration
There are two types of external calibration. One uses a set commercially produced standards and the other uses a set of well characterized reference materials that have similar matrix to the unknowns. In either case, the standards are used to create calibration curves that will be used to calculate the concentrations of the elements of interest.

The advantage of using commercially produced standards to generate the calibration curves is that their concentration is well characterized. In addition, the user can prepare solutions that cover the compositional range in the unknown samples. However, the user must be aware that the response of the ICP-MS is highly sensitive to matrix effects. The intensity of the signal at a given isotope not only depends on the abundance of that isotope, but also the matrix of the solution can enhance or suppress the response.

The standard reference materials (SRM) should be prepared by the same method as the unknowns. These standards can be used for drift corrections and to calculate the analyte concentrations in the unknowns. The advantage of using SRMs to calculate the calibration curves is that the matrix effects are readily taken into consideration, as long as the SRMs have similar matrices as the unknown samples.

3.3. Standard Addition
Standard addition is one of the most precise methods for determining the composition of an unknown sample.

This calibration strategy consists of "spiking" the unknown solution with known amounts of the analyte(s) and comparing the signal response of the un-spiked and spiked unknown solutions.

When doing standard additions, the amount of unknown solution needed is doubled. One portion of the unknown solution should not be “spiked" and another portion of the unknown solution should be “spiked."

3.4. Isotope dilution
Isotope dilution is the optimum method of calibration.

It requires that the sample be "spiked" with a solution of known elemental concentration, and whose isotopic composition has been enriched in one of the isotopes of the elements being analyzed.

Isotope dilution can only be used if the analyte has two or more isotopes, and if there is a "spike" solution enriched in one of the isotopes of every element of interest.

LASER ABLATION SAMPLE PREPARATION

In general, one of the largest benefits of laser ablation (LA) ICP-MS is that sample preparation is usually minimal, as long as the sample is relatively homogenous or the region of interest can be identified in the sample (e.g. minerals in thin section).  Consult with lab manager for any special sample preparation required for specific types of samples.

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Sample Introduction Systems

1. Autosampler
Features: Cetac ASX500 . Random access capability, flexible rack configuration, low volume rinse station, fully automated.
Applications: aqueous samples.

2. Concentric nebulizer
Features: This pneumatic nebulizer is the standard sample introduction system in ICP-MS. This nebulizer is used in combination with glass expansion chamber and torch.
Applications: aqueous solutions with low total dissolved solids (<0.1%)
Considerations: uses about 1 mL/min, relatively long rinse times are needed, prone to memory effects by some elements, oxides formation has be monitored.

3. Laser Ablation
Features: Cetac LSX 200 . The laser system is Q-switched Nd:YAG UV laser (266 nm) with variable sampling spot diameter (5 - 400 um).
Applications: solid samples (mineral grains, thin sections, glasses , bones)
Consideration: the analyst needs to know the concentration of at least one element in the samples and standards. This element is used as an internal standard.

4. Direct Injection Nebulizer
Features: Cetac Microneb 2000. The DIN is useful when limited amount of sample is available (10-20 microliters/min) and also when high throughput is required (100% delivery efficiency).
Applications: aqueous samples, memory prone elements (B, Hg, I), liquid chromatography.
Consideration: high oxide levels.

5. Ultrasonic Nebulizer and membrane desolvator
Features: Cetac U-6000 AT+. The aerosol introduced to the ICP-MS by the USN is almost free of volatile organic solvent. The USN reduces polyatomic (oxide) interferences and increases the sensitivity.
Applications: aqueous samples, analytes in solvents (e.g. kerosene, methanol, THF, n--MP, IPA).
Considerations : higher volumes of solution needed (> 5 mL).

6. Micro-Concentric Nebulizer
Features: MCN-6000 and Cetac ASX-100 autosampler . The MCN requires small sample volumes (<100 uL/min). It is fully automatic and constructed of inert material to HF. Membrane desolvator removes solvent from aerosol stream reducing oxide interferences. Increases sensitivity.
Applications: aqueous samples with low total dissolved solids, low volumes.
Considerations: long rinse time.

7. V-Groove Nebulizer
Features: appropriate to use when the solution contains high dissolved solids, resistant to blockage.
Applications: slurries.
Considerations: coarse particle size.

8. Inert Sample Introduction System
Features: this system is used when corrosive acid solutions are analyzed, or when determining elements for which the other sample introduction systems produce high background levels (e.g. B).
Applications: aqueous solutions

9. Hydride Generator
Features: Cetac HGX-100 . The HGX is a gas liquid separator. A peristaltic pump supplies precise flow of reagents and sample, providing consistent hydride generation.
Applications : gas samples of, for example, Ge, As, Se , Sn, Sb, Te, Pb, Bi, Hg, Re, Os.
Considerations: the analyte must be in the proper oxidation state.

 

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