University of Maryland
Department of Geology
GEOCHEMISTRY LABORATORIES


The Geochemistry Laboratories (GL) of the Department of Geology undertake the preparation and elemental and isotopic analysis of a wide range of materials. The mission of the GL is to produce the highest quality elemental and isotopic data, to teach students and visitors the techniques involved in gathering such data, to maintain itself as a world-class elemental and isotope measurement facility that develops new methods and instrumentation in this field.

The main areas of research of the GL include studies of the Earth’s core, mantle and crust, and of the atmosphere/hydrosphere. We also contribute to the understanding of the chemical evolution of the solar system via studies of lunar, Martian and asteroidal materials.

PEOPLE

The faculty/staff currently engaged in research in the GL include:

Richard Ash, Andrew Campbell, James Day, James Farquhar, Jay Kaufman, Sang-Tae Kim, Aaron Martin, Andy Masterson, Bill McDonough, Sarah Penniston-Dorland, Igor Puchtel, Roberta Rudnick, Satoshi Saito, Richard Walker, Brendan Williams, Keiko Yokoyama, Tetsuya Yokoyama and Aubrey Zerkle.

FACILITIES

There are 3 separate mass spectrometry (Thermal Ionization, Gas Source, Plasma) facilities within the Geochemistry Laboratories, along with laboratories for the chemical processing of samples (5), mineral separation (2) and rock preparation. These labs are all located on the ground floor of wing 2 of the Chemistry Building.

Thermal Ionization Mass Spectrometry Laboratory: This laboratory consists of three thermal ionization mass spectrometers: an NBS-design single-collector mass spectrometer, a VG Sector 54 mass spectrometer with 7 faraday collectors (see IGL) and a ThermoElectron Triton with 9 Faraday cups. These mass spectrometers use hot metal filaments to ionize highly-purified elements extracted from mineralogic matrices. The ions are then introduced into magnetic sector mass spectrometers for high precision isotopic measurement. The Triton is capable of making isotope ratio measurements with precisions to as low as ±3 ppm .

Gas Source Mass Spectrometry Laboratory: This laboratory has five separate instruments, along with their associated sample introduction apparatus. One of these (a GV Isoprime) is dedicated to dual inlet (DI) measurements, particularly for the automated analysis of the isotopic composition of large numbers of carbonate (C, O) and water (O, H) samples to high analytical accuracy and precision. The system includes an automated manifold device for the extraction and sequential measurement of gas samples prepared off-line. The second GV Isoprime mass spectrometer utilizes continuous flow (CF) inlet systems coupled with high temperature EA combustion or pyrolysis ovens for the automated isotopic analysis of organic matter (C, N, S, O, H), as well as mineral sulfates (S, O), sulfides (S), nitrates (N, O), phosphates (O), and waters (H, O – through a separate liquid injection interface). Another peripheral that acts as a head space gas extractor allows for the automated analysis of dissolved inorganic carbon (C) in water, as well as a back up device for additional carbonate and water samples typically run on the DI system. In addition, a continuous flow VG Optima with a 20 port inlet manifold has recently been added to the facility. A Finnigan Delta plus and a Finnigan MAT 253 (both with DI and CF capabilities) are dedicated to high precision analysis of rare isotopes of oxygen (17O) and sulfur (33S and 36S) for atmospheric, environmental, geochemical, and cosmochemical applications. Laser ablation capabilities are available for spot analysis.

Plasma Laboratory: This laboratory is devoted to inductively-coupled plasma mass spectrometry (ICP-MS). This type of instrument uses high temperature plasma to ionize elements for introduction into the mass spectrometer for isotopic or elemental analysis. This laboratory houses a Nu Instruments Nu Plasma multi-collector ICP-MS and a ThermoElectron Element 2, a single collector instrument. The Nu Plasma instrument is equipped with 12 faraday cup collectors and 3 ETP electron multipliers. Also installed are 2 laser ablation systems (UP 213 and UP 193), 2 high-temperature desolvating nebulizer systems (Aridus and Apex) and 2 low-temperature spray chambers (Scott-double pass and cyclonic). The UP 213 laser ablation system uses a Nd:YAG crystal and 3 harmonic generators to deliver 213 nm light to spot (5 to 350 micron diameters) or line traces. The UP 193 laser ablation system uses a TUI excimer laser with ArF gas to deliver 193 nm light to spot (4 to 400 micron diameters) or line traces. These various sample introduction systems provide us with the capabilities for the analyses of either solid or liquid samples.

Chemical processing lab: Some samples for isotopic analysis are purified in one of two adjoining 500 sq. ft. clean laboratories (CHEM 0214 and 0216). These rooms are supplied with HEPA filtered air, contain a total of five class-100 vented laminar flow hoods, two chemical fume hoods, one water washed hood for use of perchloric acid, twenty individual work stations (with fume extraction), two Milli-Q water purification systems, a Mettler AE240 balance and four sub-boiling stills (quartz and teflon).

A separate 500 sq. ft. chemical preparation laboratory (CHEM 0226) is dedicated to the isolation of carbonate and organic matter from geological samples for elemental and stable isotope analysis. In particular, this laboratory is dedicated to the preparation of stratigraphic suites of marine carbonates and organic-rich siliciclastics for chemostratigraphic research. This facility includes: Struers Labopol-21 two-wheel grinding apparatus; ServoProducts 7170 drill press; Thermolyne FA 1635 combustion oven; VWR utility drying oven; Mettler AB 104 balance; glass blowing bench; dedicated distillation bench; glass distillation lines with MKS baratron pressure transducers and Edwards pirani pressure gauges; Soxhlet extractor and Buchi rotoevaporator; Fisher Scientific centrifuge; and two six foot Kewaunee fume hoods for acid and solvent extractions. This laboratory routinely employs undergraduate assistants to assist in the preparation and analysis of thousands of samples each year.

A 500 sq. ft. chemical preparation laboratory (CHEM 0230) is used for chemical extraction and preparation of sulfur samples and oxygen samples by a variety of techniques. This laboratory is dedicated to chemical preparation of samples for atmospheric, environmental, geochemical, and cosmochemical research. It includes a variety of gas extraction manifolds, gas chromatography, UV lamps for photochemical experiments, wet chemical, and fluorination capabilities.

An additional sample preparation laboratory (CHEM 0227) is a 250 sq. ft. room adjacent to the ICP-MS laboratory and is used for sample preparation for ICP-MS analyses. It contains a recirculating fume hood, a Milli-Q water purification system and a Mettler AG204 electronic balance.

Mineral Separation and Rock Preparation Laboratories: These labs include conventional jaw crusher and disk mill, tool steel and alloy mortar and pestles, SPEX Industries Shatterbox with agate and alumina grinding chambers, Leco diamond slow-speed saw for cutting iron meteorites, Wilfley table, high density liquids (methylene iodide, bromoform and Na polytungstate), a Frantz Co. magnetic barrier separator, a Buehler automated polisher, and a stereo microscope for hand-picking separates. Elsewhere in the Department of Geology are five rock saws of various sizes and facilities for making petrographic thin sections.

Last Modified: January 2008