MCI Instrumentation: Supporting Smithsonian Science

 

 

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.

 

 

 

 

 

Analytical Technique

Instrumentation

Application

SEM

Scanning Electron Microscopy,

 

SEM-EDS

SEM-Energy Dispersive Spectroscopy,

 

SEM- µXRF

SEM-micro X-ray Fluorescence Spectrometer

Hitachi S-3700N Variable Pressure Scanning Electron Microscope w/Bruker EDS and IXRF fX series micro-XRF

 

 

 

 

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.

 

 

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

 

 

 

 

 

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.

 

ED-XRF

Energy Dispersive X-ray Fluorescence Spectrometer

 

ElvaTech, ElvaX ED-XRF

 

 

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.

p-XRF

Portable X-ray Fluorescence Spectrometer

Bruker Tracer III-V ED-XRF

 

 

 

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.

 

XRD

X-ray Diffraction

 

Rigaku D/MAX-RAPID XRD

 

 

 

Used for identification of crystalline structure in inorganic materials; especially useful for pigments, minerals, and corrosion products.

 

 

Figure: Typical XRD pattern for dolomite.

 

Raman Spectroscopy:

 

FT-Raman

&

Dispersive Raman

 

Thermo Nicolet Almega XR Dispersive Raman Spectrometer

 

 

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.

Thermo

 

 

FTIR

Fourier Transform Infrared

Thermo Nicolet 6700 Fourier Transform Infrared Spectrometer with Centaurus microscope and Golden Gate micro Attenuated Total Reflectance (ATR) accessory.

 

 

 

 

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.

 

Window25

 

Figure: Comparison of FTIR spectra. Top: a palmitic acid standard; Bottom: sample from an ethnographic object.

 

DSC

Differential Scanning Calorimetry

 

DTA

Differential Thermal Analysis

 

TGA

Thermo-Gravimetric Analysis

 

 

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.

GC

Gas Chromatography

 

 

GC/MS

Gas Chromatography Mass Spectrometry

 

 

Py/GC/MS

Pyrolysis Gas Chromatography Mass Spectrometry

 

 

 

 

 

 

 

 

Instrument 1-Agilent 5890N GC with Agilent 5975 quadrupole mass spectrometer and CDS Pyroprobe 5150 pyrolyzer

 

 

GC/MS is an 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). 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.

 

Instrument 2-Agilent 5890 GC

 

 

 

Instrument 3-Agilent 5890 GC

 

 

IRMS

Isotope Ratio Mass Spectrometry

 

Instrument-1 Thermo Delta V Advantage with Conflo-IV Interface, and Costech EA

 

 

 

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.

 

 

Instrument-2 Thermo Dual inlet Delta V Advantage with Conflo-IV Interface, GasBench II with GC PAL autosampler, and Thermo TC/EA

 

 

 

EA

Element Analyzer

 

Costech ECS 4010 CHNOS Element Analyzer

 

 

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.

Radiography

 

 

 

 

 

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.

 

3-D Scanning

 

Breuckmann GmbH  triTOS-HE structured light scanner

 

 

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, Republic of Georgia.

 

Optical Microscopy

Multiple microscopes at MCI

 

 

 

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.

 

 

3-D Microscopy

 

 

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)

Micro-Scale Color Fading Tester

 

IMG_1405.JPG

 

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).

 

 

 

 

 

Weather-ometer

 

Atlas Ci4000 Xenon Weather-Ometer

 

 

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.

 

 

Coming Soon

 

Analytical Technique

Instrumentation

Example

Portable Raman

 

 

 

GC Head Space Analyzer

 

 

 

FTIR Gas Cell

 

 

 

Computed Radiography