Geochemistry Analytical Laboratory (GAL)

The Geology and Geophysics Department at the University of Wyoming supports state-of-the-art instrumentation and laboratories for chemical analysis, of aqueous and some solid materials Quantitative, semi-quantitative, and qualitative chemical analyses are performed on a variety of instruments in the Aqueous Geochemistry Lab. We can analyze for most inorganic elements in aqueous samples, and organic elements in solid samples. We offer training in many of the instruments available in the lab.

Most of our instruments are networked for ease of data transfer and processing, and extensive computer hardware and software are available to support all of the instruments.

Laboratory Personnel:

Janet Dewey: jdewey2@uwyo.edu  Phone: 307.223.2265

 

Inductively Coupled Plasma Optical Emission Spectrometer (ICPOES)

Applications:  This instrument is used for quantitative chemical analysis of aqueous solutions. Samples are vaporized in an argon plasma and elements are quantified by light emission at characteristic wavelengths when the excited atoms transition to a lower energy state. Quantification is based on the principle that there is a proportional relationship between signal intensity and concentration. This technology can handle a wide variety of matrices (including organic, concentrated acids, HF, bases, and high dissolved solids, among others). The strength of this instrument is that the user can quantify a wide range of elements and concentrations simultaneously. Detection limits for most elements are in the parts-per-billion (ppb) ppb range and upper limits may be as high as hundreds of parts-per-million (ppm). Any number of elements can be included in an analysis. 

Instrumentation:  Perkin Elmer Optima 8300 dual view spectrometer. Sample introduction systems are quickly interchangeable to accommodate different matrices. Data acquisition and data processing are performed using Perkin Elmer PC-based Syngistix software.

Sample Requirements:  For optimal results, samples should be in stable aqueous solution with minimal matrix variability. For example – high pH and low pH samples should be analyzed separately. Samples that are high in dissolved solids, organic, or volatile (e.g. alcohols) may require dilution or other samples pre-treatment. Please contact the laboratory to discuss your particular application. 

 

Inductively Coupled Plasma Mass Spectrometer (ICPMS)

Applications:  The inductively coupled plasma mass spectrometer is also used for quantitative chemical analysis of aqueous solutions, however the technology, sample requirements, and detection limits of the instrument are different than that of ICPOES. Samples are vaporized in an argon plasma, however elements are differentiated based on their mass-to-charge ratio. Quantification is based on the principle that there is a proportional relationship between signal intensity and concentration. Detection limits for most elements are in the parts-per-trillion (ppt) range. Any number of elements can be included in an analysis.

Instrumentation:  Thermo iCAPRQ single quadrupole mass spectrometer equipped with a He collision cell. Elements may be analyzed in standard or kinetic energy dispersion (KED) mode. In KED mode, helium is used as a collision gas to remove large molecules that create polyatomic interferences (e.g. ArCl mass = 75 and As mass = 75). 

Sample Requirements:  For optimal results, samples should be in stable aqueous solution with minimal matrix variability. Samples that are high in dissolved solids, organic, or volatile (e.g. alcohols) may require dilution or other samples pre-treatment. Please contact the laboratory to discuss your particular application. 

Aqueous sampled should have less than 0.2% total dissolved solids. However, because instrument detection limits are in the ppt range, most samples can be diluted without loss of data. At this time, the instrument is not equipped to handle hydrofluoric acid, concentrated acids, or concentrated bases.

 

 

 

 

 

 

Gas Chromatography Mass Spectrometry (GCMS)

Applications: GCMS is used for a wide variety of applications (e.g. geological, pharmaceutical, etc.) however our instrument is optimized to quantify straight-chain alkanes from C11-C36 (or thereabouts). Samples in solvent matrices (e.g. hexanes) are volatilized in a heated sample introduction system, then passed through a gas chromatography column for separation of analytes. Analytes are identified and can be quantified by chromatography alone; however the capabilities of the mass spectrometer permit more precise identification of the organic molecules.

Instrumentation: The lab houses a ThermoElectron Trace ISQ GCMS equipped with a programmable temperature (PTV) inlet, a TG-5MS column within the GC, and a single quadrupole mass detector. The system is operated through two computer interfaces: ISQ dashboard controls the main mass spectrometer operation and Chromeleon 7 integrates the GC and MS and performs analytical and data processing tasks.

Sample Requirements: Samples must be dissolved or extracted in appropriate solvent; the GC column is incompatible with aqueous samples. Most samples must be diluted with solvent prior to analysis because samples with high concentrations will overwhelm the mass analyzer.

Ion chromatography

Applications: This instrument is for quantitative analysis of common anions and/or cations in aqueous samples. Aqueous samples are carried via a charged fluid (mobile phase) and introduced into a separation column which is packed with ion exchange resins (stationary phase). Constituent ions separate over time within the column based on their relative affinities for the mobile or stationary phase. Quantification is achieved by electrical conductivity.  Quantification is based on the principle that there is a proportional relationship between conductivity and concentration. Detection limits for most anions are in the 0.1-0.4 parts per million range.

Instrumentation: Our Thermo ICS 5000 is equipped with a syringe auto sampler, a self-regenerating suppressor, and a conductivity detector. Sample volumes vary, but most quantifications use 10, 25, or 50 uL injection volume.

Sample Requirements: For accurate results, samples should be similar to that of water. We can analyze samples that range from fresh water to hypersaline. Samples that contain organics or high dissolved salts will be diluted.

 

Flash Combustion Elemental Analysis

Applications: Flash combustion elemental analysis (FCEA) allows quantification of nitrogen, hydrogen, carbon, and sulfur in powdered samples. Several milligrams of powdered sample are encapsulated in tin and combusted in a furnace in the presence of excess oxygen and catalysts. Catalytic combustion temperatures reach 1400-1600⁰C. Evolved gases are separated into nitrogen, carbon, hydrogen, and sulfur in a gas chromatography (GC) column, and quantified by thermal conductivity detection. Results are given in weight percent of each element. A method for total organic carbon (TOC) is available.

Instrumentation: The lab houses a Costech Analytical ECS 4010 equipped with a zero-blank auto-sampler. Sample weights are obtained using a Sartorius microbalance capable of measurement to the thousandth of a milligram.

Sample requirements: Samples should be dried and ground to pass a 60 mesh sieve; 100 mesh is preferable for sulfur analysis. Results are in weight percent, thus the weighing step and having dried samples is critical. If natural soil or rock samples were treated with chemicals, please inform the lab because the additives may complicate the chromatography and poison the catalysts.

 

Flame Atomic Absorption

Applications: Flame atomic absorption (FAA) quantifies part-per-million concentrations of a single element in aqueous solutions. Samples are vaporized in an air-acetylene or nitrous-oxide acetylene flame. Elements are quantified by light absorption at characteristic wavelengths when atoms transition from ground state to a higher energy state. A lamp is used for excitation, and lamps are generally element specific. Sample volume is variable depending on the application.

Instrumentation: Our lab is equipped with Perkin Elmer PinAAcle 900F.  Data acquisition and data processing are performed using Perkin Elmer PC-based WinLab software.

Sample Requirements: For optimal results, samples should be in stable aqueous solution with minimal matrix variability. For example – high pH and low pH samples should be analyzed separately. Samples that are high in dissolved solids, organic, or volatile (e.g. alcohols) may require dilution or other samples pre-treatment. Please contact the laboratory to discuss your particular application. 

  

 

Accelerated Solvent Extraction (ASE)

Applications: Accelerated solvent extraction enables removal of organic matter from solid materials. Extraction is achieved under high-pressure (1500 PSI) with the addition of solvents. Typical uses included extraction of hydrocarbons from shale source rock for purposes of analysis by gas chromatography mass spectrometry (GCMS).

Instrumentation: The Thermo Electron ASE 350 permits automated extraction of up to 24 samples and accommodates sample sizes of 1-100g. We have cell sixes of 1, 5, 10, and 23 ml to accommodate a variety of sample types.

Sample Requirements: Almost any solid material (rock, tissue, etc.) can be extracted, however sample preparation will vary. Chipped or ground, dried samples are packed with inert sand or quartz boiling beads to fill the excess volume in the sample cell. A variety of solvents (e.g. methanol, dichloromethane, etc.) may be used to suit your extraction needs.

 

 

 

 

Macro Thermogravimetric analyzer (TGA)

Applications: Macro TGA enables quantification of weight-loss in solid materials at pre-programmed temperatures. Typical uses are to determine moisture, volatiles, and ash in coal (e.g. ASTM D-7852) and Loss on Ignition of soil and tissue samples.

Instrumentation: The LECO TGA 801 can hold up to 19 samples. Minimum sample size is typically 1 gram. Samples are pre-weighed using an internal balance and then weighed again at each pre-programmed temperature increment. LECO software permits user-defined programming. Data outputs are user-defined and include a graphical display.

Sample Requirements: Almost any solid material (rock, tissue, etc.) can be analyzed, however sample preparation will vary. Most samples should be air-dried and ground to pass a (U.S.) 60 mesh (250 micron) sieve. Wet samples may require more sample.