Services, Equipment and Scientific Methods

Overview of Services

New methods based on mass spectrometry are used to measure very low concentrations of contaminants in water. The facility currently supports two gas chromatography and two liquid chromatography mass spectrometry (LC/MS) systems for organic contaminant analysis.

Recently developed methods include analysis of pharmaceuticals, steroid hormones, cyanotoxins, and herbicides. An inductively coupled plasma-mass spectrometer (ICP-MS), added for trace element and heavy metal analysis, is interfaced with a liquid chromatograph system and hydride generator to provide methods for elemental species determination. Natural variations of the abundance of hydrogen, carbon, nitrogen, and oxygen isotopes can help researchers discover the origin, transformation, and environmental movement of these elements.

Stable isotope analysis is used for “fingerprinting” sources of groundwater contaminants such as nitrate and in studying chemical reactions and metabolic processes of contaminants. WSL stable isotope equipment includes two dual inlet and two continuous flow mass spectrometers with automated sample preparation systems.

A new dual inlet mass spectrometer was added in 2007 and provides capabilities for small sample analysis while the continuous flow systems allow for more rapid and less expensive isotope analysis.

Recently developed stable isotope methods include carbon and oxygen isotope analysis of dissolved and solid carbonates; hydrogen, carbon, and oxygen isotopes in nitrate, phosphate and organics.

Stable Isotope and Noble Gas Mass Spectrometry

Stable isotope analysis can provide powerful tools for water science research. This equipment focuses on high precision measurements of naturally occurring isotopes of hydrogen, carbon, nitrogen, and oxygen. Natural variations of the abundance of these isotopes can help discover the origin and flow of these elements in the environment.

Stable isotope analysis often “fingerprints” sources of contaminants such as nitrate. Stable isotope analysis also is used in studying chemical reactions and metabolic processes.

The WSL offers methods for stable isotope analysis of gases, water, and solids. The lab is well known for its methods for determination of the isotopic composition of nitrate and ammonia nitrogen to support the investigation of nitrate contamination of groundwater and environmental fate and transportation.

Some of the lab’s most recent equipment includes automated sample preparation systems to reduce time and expense in preparing water samples for isotopic analysis.

Instrumentation used in the Stable Isotope Mass Spectrometry facility includes two dual inlet and two continuous flow mass spectrometers.

An obsolete Nuclide 6-60-RMS mass spectrometer was replaced with a new dual inlet Isoprime in 2006. Current major instrumentation includes:

  • VG Optima dual inlet isotope ratio mass spectrometer is the primary instrument available for nitrogen isotope work, but may also be used for hydrogen, carbon and oxygen analyses. Its dual inlet and cryo-focusing capability provide the high sensitivity required for small (micromole) samples.
  • AP2003 with Isoprep is a continuous flow isotope ratio mass spectrometer with a computer-controlled system enabling automated preparation and analysis of water and gas samples for carbon-13 and oxygen-18 analysis. A second automated sample preparation system, the Isoprep C, was added to expand this capability to rapid analysis of carbonate samples.
  • GV Isoprime continuous flow mass spectrometer with a Eurovector PyrOH elemental analyzer using a chromium reduction furnace designed for automated high-precision determination of the deuterium content of water. A second Eurovector solids elemental analyzer was added to expand this capability to analysis of deuterium, carbon, nitrogen and oxygen isotopes in solids (plants, salts, sediments).
  • GV Isoprime dual inlet isotope ratio mass spectrometer is state-of-the-art for small sample stable isotope analysis and will be used for both nitrogen and carbonate stable isotope analysis where high sensitivity is required.
  • Thermo Helix SFT noble gas mass spectrometer for high sensitivity determination of helium and other inert gas isotopes. This instrument interfaces with an ultra-low temperature cryogenic gas extraction and purification system primarily for groundwater age-dating. The purification system includes a Hiden Analytical quadrupole mass spectrometer used to quantify dissolved gases for recharge temperature determination and evaluation of excess-air and denitrification effects in shallow groundwater. The purpose is to more accurately measure and access renewal aquifer recharge rates.

Other high vacuum preparation systems in the WSL are essential for conversion and purification of samples for isotope analysis.

While the automated preparation systems described above reduce dependence on off-line preparation methods, these systems will continue to be used where automated preparation cannot be used.

Environmental Mass Spectrometry and Chromatography

The mass spectrometer is the most widely accepted detector for environmental analysis. Methods based on mass spectrometry are among the most powerful, sensitive, and reliable available for water science research.

Instrumentation in this lab is used for developing and applying methods to accurately measure very low concentrations of organic contaminants such as pesticides, munitions waste, both steroids and pharmaceuticals from concentrated animal feeding operations (CAFOs), toxins, gasoline additives, and degradation products in a wide variety of matrices.

Many new methods have been developed in this facility using state-of-the-art instrumentation for analysis of these and other emerging contaminants. An older Agilent 5970 GC/MS has been recently moved into the stable isotope facility and will be modified for the development of new methods (compound specific isotope analysis). Major instrumentation in this area includes:

  • Hewlett Packard 5972 Gas chromatograph/mass spectrometer is the primary instrument used for trace level pesticide analysis.
  • Thermofinnigan LCQ Ion trap Liquid chromatograph/mass spectrometer system allows for trace level detection of explosives residues, pesticides, antibiotics and compounds formed during their degradation. The ion trap permits tandem mass spectrometry (MS/MS) for improved selectivity and multiple fragmentation capability (MSn) to characterize compound structures and has proven quite useful for identification of unknowns in contaminant remediation experiments. An INUS BetaRam radioactivity detector was added to permit unequivocal detection and mass spectrometer characterization of radioactively labeled compounds used in remediation experiments.
  • Micromass Quattro Micro Triple quadrupole liquid chromatograph/mass spectrometer is a state-of-the-art instrument capable of highly sensitive and selective analysis of polar (water soluble) organics such as explosives, pharmaceuticals, hormones, surfactants and other emerging contaminants. A Spark Holland Symbiosys Environ online extraction system was later added to allow more rapid extraction and analysis of samples for this instrument. This capability has also lead to even more sensitivity in methods developed through this technology because of the ability to easily concentrate and immediately analyze contaminants.
  • Agilent 5973 Gas chromatograph/mass spectrometer has both electron and chemical ionization sources and a newly designed inert source that improves sensitivity by an order of magnitude. This GC/MS was installed with a Leap CombiPAL autosampler that permits automated headspace and solid phase microextraction in addition to the traditional liquid solvent injection of samples. This instrument is used for gasoline oxygenate analysis, along with methods for volatile organics and pesticides. An OI purge and trap autosampler, was installed on this instrument for analysis of volatile organics.

Other Chromatography equipment

  • Hewlett Packard 5890 GC with flame ionization and electron capture detectors is used for headspace analysis of solvents and gases.
  • Gow Mac 550P GC with thermal conductivity detector used for analysis of gases.
  • Trace Analytical RGA3 GC is a specially designed gas chromatograph for analysis of dissolved hydrogen gas in water.
  • Agilent 6890 GC with a high sensitivity micro-electron detector has been modified with a custom-built vacuum extraction system for ultra-trace level analysis of Freon for groundwater age dating. It is also used for analysis of halogated compounds such as SF6 used as environmental tracers.
  • Waters 2695 HPLC with photodiode array detector is used for analysis of compounds that do not require MS detection and includes a Spectrum fraction collector for purification of organic compounds. Each of the LC/MS systems are also are equipped with a Waters 2695 HPLC as the separations unit and facilitates operation and maintenance issues.
  • Varian 3600CX, with 8200 autosampler and multiple detectors (ECD, FID, TCD, and NPD) can be used where mass spectrometric detection is not required for volatile organics and gases.

Wet Chemistry Lab

Used for preparation of water samples for trace organics analysis, and for analysis of water using ion chromatography, spectrophotometry, and automated analyzers. Equipment operated in this lab includes:

  • Dionex ICS-90 Ion Chromatograph with PeakNet data system is the primary instrument for analysis of major anions.
  • Seal AQ2 Autoanalyzer is a new generation of autoanalyzer used for rapid and precise colorimetric analysis of hundreds of water samples for ammonia, nitrate, phosphorus and other water quality parameters.
  • Lachat 8500 Quikchem Flow Injection Autoanalyer (FIA) is used for high throughput and low cost nutrient (nitrate, phosphate, ammonian, TN) analysis in water and soil extracts.
  • Ol Model 1010 Carbon Analyzer with autosampler is used for automated analysis of organic carbon in water.
  • Perkin Elmer AAnalyst 400 Spectrophotometer is primarily used for determination of cations and dissolved elements.
  • Labconco RapidVap Concentrator is used for evaporating solvents

Wet Chemistry Lab

A GVI Platform XS collision cell ICP-MS is state of the art for highly sensitive trace element analysis and is use for analysis heavy metals and toxic contaminants such as arsenic.

The collision cell technology removes many of the isobaric interferences common in earlier ICP-MS systems and expands the range of elements that may be quantified. The Platform XS is interfaced with CETAC ultrasonic nebulizers, a CETAC cold vapor and hydrid generation system, and can be used with a SSI liquid chromatography system for development of speciation methods based on ion exchange and metal chelation chromatography.