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MCI Instrumentation:
Supporting Smithsonian Science |
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MCI has a wide range of
analytical methods available for the examination and analysis of materials
and objects from museums, ethnographic, archaeological contexts, and scientific
collections. These techniques range from optical microscopy and digital image
analysis to more recent methods such as ICP-MS (Inductively
Coupled Plasma Mass Spectroscopy) and handheld X-ray fluorescence. For more information about instrumentation at MCI, click on one
of the links below.
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Analytical
Technique |
Instrumentation |
Application |
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SEM Scanning
Electron Microscopy, SEM-EDS SEM-Energy
Dispersive Spectroscopy, SEM-
µXRF SEM-micro
X-ray Fluorescence Spectrometer |
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Used for low- and high-magnification imaging at variable
pressure (<1–270 Pa). The sample chamber can accommodate objects up to 30
cm in diameter and 8 cm in height. This instrument is capable of imaging and
analyzing intact objects non-destructively, without the need to sample,
embed, polish and coat as in traditional SEM-EDS. The EDS and µXRF are used for inorganic elemental mapping and analysis of
samples. Depending on the nature and preparation of the sample, EDS analyses can be qualitative or fully quantitative,
with limits of detection possible down to 0.5%; in some cases detection
limits of 10 ppm are achievable with the µXRF.
Figure:
SEM-EDS elemental map of oxygen (orange), carbon (green) and phosphorus (purple)
in degraded cellulose acetate. The crystals are enriched
in phosphorus relative to the surrounding area. |
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ICP-MS Inductively
Coupled Plasma-Mass Spectrometry LA-ICP-MS Laser
Ablation Inductively
Coupled Plasma-Mass Spectrometry |
Perkin
Elmer Elan 6000 ICP-MS & CETAC LUV 266 nm LA
system
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Able to measure most elements on the periodic table.
ICP-MS is especially useful for analysis of inorganic materials, such as
metal alloys, glass, ceramics, pigments, and minerals. Samples
can be introduced to the spectrometer as a solution
or in solid form via laser ablation, which is minimally invasive to the
object. Detection
limits range from %-level to ppb or ppt range for
many elements.
Figure: Laser
Ablation scar after the analysis of glass.
The total area impacted is ca. 0.75 mm x 0.75 mm. |
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ED-XRF Energy
Dispersive X-ray Fluorescence Spectrometer |
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Portable
benchtop XRF instrument used for non-destructive elemental
analysis in the laboratory or in the or collection
facilities. XRF is especially useful for identifying inorganic compounds such
as metal alloys, glass, ceramics and pigments. |
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p-XRF Portable
X-ray Fluorescence Spectrometer |
Bruker
Tracer III-V ED-XRF
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Portable
handheld XRF instrument used for non-destructive elemental analysis; p-XRF is
especially useful for identifying inorganic compounds, such as metal alloys,
glass, ceramics and pigments.
Figure: Plot
of zirconium and strontium concentrations (ppm) for 2154 obsidian artifacts
analyzed by portable XRF. Each cluster
corresponds to a specific geologic outcrop. |
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XRD X-ray
Diffraction |
Rigaku
D/MAX-RAPID XRD
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Used for identification of crystalline structure
in inorganic materials; especially useful for pigments, minerals, and
corrosion products.
Figure: Typical XRD pattern for dolomite. |
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Raman Spectroscopy: FT-Raman & Dispersive Raman |
Thermo
Nicolet Almega XR Dispersive Raman Spectrometer
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Raman
is used to provide qualitative and quantitative information on organic and
inorganic molecules in a given sample matrix. Raman is particularly useful
for examining polymers, monomers, and other modern materials found in
museums, as well as proteinaceous and keratinaceous materials, pigments, and some corrosion
products. Spectra
are very specific; chemical identifications can be
performed by using search algorithms in digital databases. Analyses
are non-destructive; little or no sample preparation is required. Fiber
optic lines can be used for analyses ‘outside of the
box’.
Figure: Typical
Raman spectrum for cellulose acetate. |
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Thermo
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FTIR Fourier
Transform Infrared |
Thermo
Nicolet 6700 Fourier Transform Infrared Spectrometer with Centaurus
microscope and
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FTIR
used to produce a "fingerprint" spectrum of different chemical compounds
within objects. FTIR is useful for characterizing organic molecules, such as
coatings, adhesives, and paint binders, and some inorganic molecules.
Figure: Comparison of FTIR spectra. Top: a palmitic acid standard; Bottom:
sample from an ethnographic object. |
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DSC Differential
Scanning Calorimetry DTA Differential
Thermal Analysis TGA Thermo-Gravimetric
Analysis |
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DSC
and DTA are used to study phase transitions, such
glass transition melts and other thermal transitions. TGA
is used to examine the characteristics of materials
such as polymers,
to determine degradation temperatures, absorbed moisture content of
materials, the level of inorganic and organic components in materials,
decomposition points of explosives,
and solvent residues. |
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GC Gas
Chromatography GC/MS Gas
Chromatography Mass Spectrometry Py-GC/MS
Pyrolysis
Gas Chromatography Mass Spectrometry HS-GC/MS
Headspace Gas Chromatography Mass Spectrometry
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Instrument
1-Agilent 6890N GC with Agilent 5975 quadrupole mass spectrometer, CDS
Pyroprobe 5150 pyrolyzer, & Agilent 7694E headspace sampler
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GC and GC/MS
are instrumental technique in which complex mixtures of chemicals may be separated, identified and quantified. The technique
first vaporizes dissolved samples or derivatives (chemically modified
samples), into gases and then separates according to their volatility (and
polarity). In MS each gas is then bombarded with electrons
so that ion fragments are formed. These ions are separated
and filtered according to the fragment masses and counted.
Interpretation of the resulting mass fragmentation patterns provides the
identification of the gases and ultimately the chemical makeup of the sample.
Py-GC/MS is
used to provide rapid analysis of solvent-insoluble samples, but is
particularly useful analysis of intractable and nonvolatile macromolecular
complexes, i.e., polymers, soils, sediments, and hair.
Figure: Pyrogram of Flo-texx, a product used as a mounting medium in
microscopy. Large peak in the center is methyl methacrylate; the large peak on the right is n-butyl methacrylate. |
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Instrument
2-Agilent 5890 GC
with ECD and NPD
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Instrument
3-Agilent 6890 GC
with FID
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IRMS Isotope
Ratio Mass Spectrometry |
Instrument-1
Thermo Delta V Advantage with Conflo-IV Interface,
and Costech EA
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Used for
high-precision isotope ratio studies of carbon, nitrogen, oxygen, hydrogen,
and sulfur (C, N, O, H, and S). C, N, O, H, and S naturally
occur as two or more stable (non-radioactive) isotopes. The stable isotope
composition of organic and inorganic substances can be used
to trace the pathways and forms that these key elements take as they are
transferred and cycled within biological and geochemical systems.
Measurements of stable isotope ratios in soils and plant samples are used to reconstruct past climates and vegetation,
evaluate physiological responses of wild and domesticated plants (and
animals), characterize energy and material transfers and transformations
among plant, animal, and microbial components of ecosystems, and understand
atmosphere-biosphere interactions. Stable isotopes record information on
biological and physical processes operating across space and time, and thus
are useful in integrative studies that span disciplines and levels of
biological organization. Rapid and precise stable isotope analysis of solid,
liquid, and gaseous materials is fundamental to many studies in physiology,
ecology, hydrology, and earth and atmospheric sciences.
Figure:
Chromatogram of N2 and CO2 isotopes in an organic standard. |
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Instrument-2
Thermo Dual inlet Delta V Advantage with Conflo-IV
Interface, GasBench II with GC PAL autosampler, and Thermo TC/EA
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EA Element
Analyzer |
Costech
ECS 4010 CHNOS Element Analyzer
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Can
be used as a stand-alone instrument to measure bulk carbon, nitrogen, oxygen,
hydrogen, and sulfur in a given sample, or as a sampling
system for IRMS that does not contaminate the sample with atmospheric
nitrogen and oxygen, especially working at very low concentrations. |
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Radiography |
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Used for the structural examination of art and
artifacts. For art works, it helps to reveal losses, replacements, and
methods of construction that may not be visible to the naked eye.
Figure:
Radiograph of an early NASA training suit. |
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3-D Scanning |
Breuckmann
GmbH triTOS-HE
structured light scanner
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Used
for high-resolution, digital, 3-dimensional documentation projects. By viewing the data files with 3D graphic software, it is
possible to view and manipulate the 3D graphic models on a computer screen, make
virtual measurements, and create virtual lighting to best study the surfaces
of the object. The 3D data also can be used to make
replicas in the positive or negative at any scale in almost any material by
computer numerical controlled milling (CNC) or rapid prototyping.
Figure:
3-dimensional representation of a 2nd century B.C.E. bronze torso
recovered from the Vani site, |
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Optical Microscopy |
Multiple
microscopes at MCI
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Used to document, describe, analyze, and identify objects;
provides unique information about the structure and state of preservation of
objects and the identity of their component materials.
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3-D Microscopy |
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Used for 3-dimensional imaging analysis; provides unique
information about the structure and state of preservation of objects and the
identity of their component materials. (Instrument purchase courtesy of Smithsonian Women’s Committee
Grant) |
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Micro-Scale Color Fading
Tester |
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Used to determine light-fastness data for
museum objects. The device consists of a reflectance spectrophotometer coupled
to an accelerated light fading micro-tester. The instrument uses fiber optics
for delivering light to the sample. Two advantages of this technique are
small spot size (< 0.4 mm) and short testing time (1-2 minutes). |
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Weather-ometer |
Atlas
Ci4000 Xenon Weather-Ometer
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Used in experiments that require artificial
aging and/or accelerated weathering. Controlled cycles of ultraviolet
radiation, light, electric arcs, water spray, and heating elements are used to simulate the natural conditions of sun,
humidity and temperature changes. Particularly useful for determining how
exhibit materials will respond to prolonged periods in museum environments. |
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Coming Soon |
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Analytical Technique |
Instrumentation |
Example |
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Portable Raman |
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GC Head Space Analyzer |
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FTIR Gas Cell |
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Computed Radiography |
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