External Services

Micro-Compositional Analysis Services

Quantitative elemental analysis of aqueous solutions by ICP-MS

Our Thermo-Fisher Element 2 sector-field ICP-MS allows for precise and accurate measurements of most elements of the periodic table, in concentrations ranging from parts per trillion (ppt) to parts per million (ppm), with capability and detection limits varying per element (and generally best for metals and heavy atomic masses).

The Element 2 has a high mass resolution capability allowing for precise and accurate quantification of light mass elements typically prone to isobaric interferences. Samples are run against calibration standards of concentration ranges matching those of theFF samples. Blanks are also run in the same analytical session, for assessment of detection limits and laboratory and instrumental elemental backgrounds. Samples are run after addition of an internal standard, for more precise quantification.

For optimal results, it is preferred that samples be submitted in a weak nitric acid matrix (~1%). Users should consult with us before submitting samples, and inform us of the nature of their samples and the expected range of concentrations of their element(s) of interest. Improper sample preparation may result in a loss of data quality and extra sample preparation time in our laboratories, with extra associated charges.

We accept natural waters, aqueous solutions from experiments, digested inorganic or organic compounds, natural or man-made.

Quantitative micro-analysis of solids and glasses by laser-ablation (LA)-ICP-MS

The ICP-MS above can be used in tandem with a Photon Machines Analyte G2 laser ablation system. The laser acts as a sampling device for the ICP-MS.

Elements can be quantified with concentrations in the order of sub-part per million to wt %, with capabilities that vary across the periodic table, as for stand-alone ICP-MS. Laser spot size can vary from 110 to 5 microns, with the largest spot sized preferred for best instrumental capability. Larger samples can also be rastered as surface scans with a wide beam, for optimal performance.

Samples are run against several calibration standards, and blank levels are subtracted to each analysis. Samples can be submitted as thin sections or 1-inch epoxy mounts. Custom sizes can be accepted after consulting with us, if they have a flat surface suitable for ablation and fit within our sample tray.

As for stand-alone ICP-MS, it is preferred that users know the matrix type of their samples and the expected concentration ranges of their element(s) of interest. Samples can consists of natural or synthetic minerals, glasses, metals, alloys, ceramics, bone and tooth tissues and fused powders.

Quantitative and semi-quantitative analyses of major elements by X-ray Fluorescence

Our Shimadzu XRF-1800 X-ray fluorescence spectrometer allows for quantitative or semi-quantitative analyses of major element compounds and some trace elements, in a variety of material types including powders, pressed powders, fused powders, films, and metal, glass or ceramics surfaces.

Sample sizes can vary from a few cm to a few mm in diameter. As with the LA-ICP-MS, results are the most robust for the largest sample sizes.

The XRF may be used in combination with the ICP-MS or LA-ICP-MS, upon user request, or at our discretion for materials of unknown composition. The XRF will only provide semi-quantitative results if no reference materials of matching compositions are available.

Imaging and semi-quantitative micro-analytical elemental analysis by scanning electron microscopy

Our JEOL JSM-5610LV scanning electron microscope provides 50x to 50,000x secondary electron microscopy imaging of samples such as micro-fossils, microscopic minerals or dust, and elemental density information of polished surfaces by backscatter electron microscopy. Our SEM is also equipped with a Thermo Ultra Dry Energy Dispersive Spectroscopy (EDS) detector, allowing for semi-quantitative micro-analysis of major elements on polished surfaces.

We can accept epoxy mounts and petrographic thin sections.

The SEM can be used, upon user request, in tandem with the LA-ICP-MS for preliminary non-destructive EDS characterization of materials. The EDS detector also allows for elemental mapping of samples.

Northern Illinois University Micro-compositional Analysis Lab Pricing (PDF)

Stable Isotope Laboratory Services

Isotope Ratio Mass Spectrometry

Isotope ratio mass spectrometry (IRMS) allows for measurements of the stable isotope ratios of light elements such as hydrogen, carbon, nitrogen, oxygen, sulfur, silicon at the natural abundance level in a broad range of samples.

Two Isotope Ratio Mass Spectrometers are used in the NIU Stable Isotope Laboratory (SIL), Thermo Fisher Scientific MAT 253 and Delta Plus Advantage. Samples can be analyzed directly in a dual inlet mode (e.g. CO2, O2, N2 gas) or after conversion to these simple gases using various online techniques. Our laboratory is equipped with Elemental Analyzer (EA, Costech ECS 4010) that converts samples designated for carbon 13C/12C and nitrogen 15N/14N isotope analyzes to CO2 and N2 (Thermo-Finnigan DELTAplus Advantage). Samples frequently analyzed using EA include plant material, animal tissues, soil. In addition to the EA, a Gas Chromatograph (GC) is coupled to the same IRMS via a combustion interface (Thermo Fisher Scientific GC-C III), which allows us to analyze the stable carbon (13C/12C) or hydrogen (2H/1H) isotopes of a single organic compound.

To analyze hydrogen and oxygen stable isotopes in organic samples (e.g. cellulose) or inorganic, for example water, Thermal Conversion/Elemental Analysis (Thermo Finnigan TC/EA) is used. Sample is converted to H2 and CO using pyrolysis reactor and directed to the IRMS for measurements (2H/1H, 18O/16O). Another sample preparation peripheral that is used online is the Gas Bench (Thermo Fisher Scientific), which is used to analyze carbonates, dissolved inorganic carbon or water for their isotope ratios of oxygen and/or carbon (18O/16O and 13C/12C). To analyze oxygen and silicon isotopes (18O/16O and 29Si/28Si, 30Si/28Si ) in quartz samples we first liberate oxygen as O2 and convert Si to SiF4 with the use of a fluorination reaction and a laser  (Photon Machines Fusion 10.6 Laser) before transferring the gasses to IRMS (Thermo Fisher Scientific MAT 253). 
Gas Chromatograph with Mass Spectrometer (Varian Saturn 3800 and 2100 IT Mass Spectrometer)

Gas Chromatograph is used for identification and quantitation of the semi-volatile compounds which are previously extracted from various environmental samples. A mixture of organic compounds in a liquid solvent is injected into an injector kept usually at a temperature between 200-300 °C. The sample instantly vaporizes and is carried in a stream of helium into a capillary column where it undergoes a separation based on the volatility and affinity of a specific compound to a stationary phase of the column. Separated compounds are transferred into an ion trap mass spectrometer, where they undergo the ionization and the detection.

Sample Submission Form

Stable Isotope Lab Pricing

Contact Us

Department of Earth, Atmosphere and Environment
Davis Hall, Room 312

815-753-0631 (undergraduate)
815-753-1943 (graduate)

815-753-1945 (fax)

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