U.S. EPA Contaminated Site Cleanup Information (CLU-IN)


U.S. Environmental Protection Agency
U.S. EPA Technology Innovation and Field Services Division

Dense Nonaqueous Phase Liquids (DNAPLs)

Detection and Site Characterization

Field Analytical Equipment: Environmental Technology Verification Reports

Adobe PDF LogoField Portable Gas Chromatograph/Mass Spectrometer, Bruker-Franzen Analytical Systems, Inc. EM640™
EPA 600-R-97-149, 105 pp, 1997

Gas chromatography/mass spectroscopy (GC/MS) is a proven laboratory analytical technology that has been used in environmental laboratories for many years. The combination of GC and MS enables the rapid separation and identification of individual compounds in complex mixtures. The GC separates the sample extract into individual components. The MS, which ionizes each component, provides the energy to fragment the molecules into characteristic ions. These ion fragments are then separated by mass and detected as charged particles that constitute a mass spectrum. This spectrum can be used in the identification and quantitation of each component in the sample extract. For nontarget or unknown analytes, the mass spectrum is compared to a computerized library of compounds to provide identification of the unknown components. Field transportable GC/MS is a versatile technique that can be used to provide rapid screening data or laboratory quality confirmatory analyses. In most systems, the instrument configuration can also be quickly changed to accommodate different inlets for media such as soil, soil gas, and water. As with all field analytical studies, it may be necessary to send a portion of the samples to an independent laboratory for confirmatory analyses. The manufacturer's name has changed from Bruker-Franzen Analytical Systems to Bruker Daltonik, GmbH, and the product model is now EM640S.

Adobe PDF LogoField-Portable Gas Chromatograph/Mass Spectrometer, Inficon, Inc., HAPSITE
EPA 600-R-98-142, 79 pp, 1998.

Adobe PDF LogoField-Portable Gas Chromatograph, Sentex Systems, Inc. Scentograph Plus II
EPA 600-R-98-145, 81 pp, 1998

Sentex Systems was bought by Inficon in 2003. Although the Scentograph series has been continued and updated, the Scentograph Plus II is no longer offered.

Adobe PDF LogoPhotoacoustic Spectrophotometer, Innova AirTech Instruments Type 1312 Multi-Gas Monitor
EPA 600-R-98-143, 75 pp, 1998

The Type 1312 utilizes photoacoustic spectroscopy for the detection of chlorinated VOCs in the headspace of a water sample. The vapors from the equilibrium headspace of a stirred water sample are circulated through the instrument's measurement cell. When a gas in the cell is irradiated with electomagnetic energy at frequencies that correspond to resonant vibration frequencies of VOC compounds in the gas, a portion of the incident energy is absorbed, causing some of the molecules of the gas to be excited to a higher vibrational energy state. These molecules subsequently relax back to the lower-energy vibrational state through a combination of radiative and kinetic processes. The kinetic energy decay process results in increased heat energy of the gas molecules and a corresponding temperature and pressure increase in the gas. The incident infrared source is modulated and the resulting pressure is also modulated. The varying pressure in the cell produces an acoustic wave that is detected with a high-sensitivity microphone. Compound specificity is achieved by using bandpass filters tuned to the energy absorption bands of target compounds, and quantification is done by measuring the intensity of the resulting acoustic signal.

Adobe PDF LogoField-Portable Gas Chromatograph, Perkin-Elmer Photovac, Voyager
EPA 600-R-98-144, 84 pp, 1998

The Voyager utilizes an equilibrium headspace technique for the analysis of VOCs in water. Instrument detection limits for many chlorinated VOCs in water are in the range of 5 to 10 mg/L. The Voyager includes an on-board processor and is encapsulated in a weather-resistant case. The GC unit weighs about 15 pounds, and the accessories for water analysis weigh about 33 pounds. Both units can be easily transported and operated in the rear compartment of a minivan. Sample processing and analysis can be accomplished by a chemical technician with one day of training; however, instrument method development and initial calibration may require additional experience and training. At the time of the demonstration, the baseline cost of the Voyager and headspace sampling accessories was $24,000. Operational costs, which take into account consumable supplies, are on the order of $25 per 8-hour day. Photovac was acquired from Perkin-Elmer in 2001 by the Carlisle Instruments Group in Waltham, MA.

Adobe PDF LogoEnvironmental Technology Verification Report: Field-Portable Gas Chromatograph, Electronic Sensor Technology, Model 4100
EPA 600-R-98-141, 78 pp, 1998

The Model 4100 GC incorporates a purge-and-trap sample introduction method for the analysis of VOCs in water. The instrument is a single-column GC with programmable temperature control and a surface acoustic wave detector. The system uses short capillary GC columns and a fast-response detector to produce a complete chromatogram in 30 seconds or less. A room-temperature water sample is sparged with a small volume of air, and the entrained VOCs are transferred to a small adsorbent trap, which is subsequently thermally desorbed and injected onto the GC column of the Model 4100. The chromatographic column separates the sample mixture into individual components. Compounds exiting the column momentarily stick to the detector surface, causing a frequency change in an oscillating crystal. The 4100 model has been updated and the company now offers it as the 4200 model.



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