NEWMOA Technology Review Committee

Advisory Opinion

Innovative Technology: Gas Chromatography Field Analysis
Date of Opinion: November 29, 2000

The purpose of this Advisory Opinion is to raise awareness of field portable gas chromatography (GC) technology and its on-site application in the Northeast.(1) This Advisory Opinion is intended to communicate Technology Review Committee (TRC) interest in the use of field portable GC technology to potential users of hazardous waste site characterization technology, such as consultants, as well as to project managers within the various state site cleanup programs. The Advisory Opinion is also intended to educate consultants and the state regulators who oversee projects about the factors that can affect the proper use of field portable GC technology.

All seven of the Northeast states participated in the development of this Advisory Opinion consensus statement. In addition, the technical information was reviewed by U.S. EPA Region I and vendors of GC technology. However, it should be noted that this Advisory Opinion is not intended to be an "approval" of this technology. The appropriateness of the use of GC technology will need to be determined on a site-by-site basis. Potential users should contact officials in the state in which the project is located to determine if there are any state-specific requirements that could apply.

Project Background:

Recognizing the need to overcome barriers to the acceptance of technology innovation, the six New England States, EPA Region I - New England, the Northeast Waste Management Officials' Association (NEWMOA) and the New England Governors' Conference signed a Memorandum of Agreement (MOA) in March 1998 to promote interstate regulatory cooperation for waste site assessment and cleanup technologies. Subsequently, NEWMOA has worked closely with EPA Region I and the Northeast Hazardous Substances Research Center (NHSRC) to increase the understanding of the factors that discourage the use of innovative technologies. NEWMOA held meetings and conference calls with NEWMOA's Waste Site Cleanup Workgroup and co-sponsored, with NHSRC, a Stakeholders Workshop held in May 1998 called "Increasing the Use of Innovative Technologies on Small Hazardous Waste and Petroleum Sites." The focus of this Workshop was on building consensus among the stakeholders regarding measures to reduce or eliminate obstacles to the use of innovative site assessment technologies.

At the May 1998 Stakeholder Workshop, participants identified the lack of an interstate forum in the Northeast to actively review technologies and communicate both public and private sector use of innovative technologies as a major impediment to the overall marketability of the newer field analytical, characterization and monitoring technologies. To address this need, NEWMOA has established the TRC, made up of one or more staff members from each of the Northeast states to coordinate state review, issue advisory opinions and disseminate information on the use of innovative technologies.

Benefits of Field-Based Site Characterization:

Regulatory and institutional barriers to the adoption of innovative hazardous waste site assessment technologies can result in increased expenditures to evaluate and remediate contaminated sites. Because innovative technologies have the potential to clean up and protect the environment and the public's health in a more cost-effective and efficient manner, finding ways to encourage their increased use is crucial. Some examples of the potential benefits of using field analytical methods to support a field investigation or cleanup verification program include:

More information about the benefits of using a field-based site characterization approach is contained in the January 3, 2000 article, Improving the Cost-Effectiveness of Hazardous Waste Site Characterization and Monitoring by the U.S. EPA Technology Innovation Office which can be found on the internet at: Additional information to support a field-based characterization approach can be found at in the Site Characterization section. Detailed information about many field-based site characterization technologies can be found in EPA's Field Analytic Technologies Encyclopedia (FATE) located on-line at All of the TRC's advisory opinions on innovative site characterization technologies are available at

Overview of Technology:

Field portable GC can be used for analysis of volatile organic compounds (VOCs) in water, soil, soil gas and ambient air. In theory, a field portable GC could be used to analyze for semi-volatile organic compounds (SVOC) such as pesticides and PCBs; however due to sample preparation needs, SVOC analysis in the field is not common. A field portable GC could be appropriate for use at hazardous waste sites to:

When GC is used in the field, a stable environment for equipment operation is needed, especially some control of the temperature that the equipment is operated in. In order to obtain consistent and comparable results, all samples should be at thermal equilibrium at a similar temperature before analysis. Depending on the project data needs and quality objectives, combined with the ambient environmental conditions, the necessary environmental control could vary from inside a truck cab or car, to in the shade, to inside the project trailer, to a mobile lab.

Gas chromatography is a separation technology, not an analytical technology in itself. After the sample is separated into its constituent compounds by the GC, it is analyzed by a follow-on detection technology. The GC processes gaseous samples and therefore, water and soil samples must be prepared to drive the contaminants into gaseous phase. The various detection technologies are discussed after the GC technology itself is presented. Sample preparation is discussed in a section after the detection technologies.

Gas Chromatography

Gas chromatography is used to separate a mixture of closely-related compounds into the individual compounds for measurement. For example, GC is often used to separate a mixture of VOCs into the individual compounds. The sample is typically introduced into the instrument through the injection port using a syringe. The injection port is heated so the analytes are vaporized and are then mixed with an inert gas called the mobile phase or carrier gas, usually nitrogen, helium or hydrogen.

The mobile phase carries the sample through a coiled tubular column where analytes interact with the material on the inside of the column called the stationary phase. The analytes are kept in the gaseous state by using an oven to keep the column temperature above the boiling point of the analytes. The rate at which the mobile phase moves through the column can be varied, higher rates are associated with faster analysis times, but lower resolution of the results. The length and diameter of the column can also vary. Typical column length is 30 to 60 meters. The shorter the column the faster the analysis time, but the lower the resolution. Columns are typically between 0.25 and 0.32 millimeters (mm) in diameter, with high resolution columns between 0.15 and 0.20 mm. Capillary columns are usually made of fused silica due to its strength and flexibility.

The stationary phase is chosen so that the components of the sample distribute themselves between the mobile and stationary phase to varying degrees. Those components that are strongly retained by the stationary phase move through the column more slowly than components that have a lower affinity for the stationary phase. The stationary phase is an organic liquid compound that is either coated on or covalently bonded to the silica surface of a capillary column. The polarities of the compounds of interest dictate the choice of stationary phase, under the rule "like dissolves like." Commonly used stationary phases include:

polydimethyl siloxane (commonly referred to as OV-1 of SE-30) for PCB or PAH separation carbowax - used for free acids, alcohols, and glycols
OV-17 - for pesticides and glycols
OV-210 - for chlorinated aromatics, nitroaromatics, and alkyl substituted benzenes
OV-3 or SE-52 for halogenated organics.

Dual column analysis is often used to confirm the identification of a compound(s) indicated by single column analysis. Dual column analysis means that two columns are used, each with a different stationary phase to increase the GCs ability to separate a wider range of compounds.

Environmental samples can have high concentrations or other constituents that can ruin column performance and require its replacement. Samples with the potential for high concentrations are typically diluted before introduction to the GC. A field screening technique, such as using an flame ionization detector (FID) or photoionization detector (PID) alone, can help identify samples that are likely to contain high concentrations. For PCB analysis of oily samples, components of the oil can ruin column performance. Another rare, but potential problem is that excessive oven temperatures can cause the stationary phase to elute from the column, called column bleed which fouls the follow-on detector, requiring its replacement.


As a consequence of the differences in analyte mobility, the sample components separate into discrete bands that can be analyzed qualitatively and quantitatively by the follow-on detection device. The compound is identified and its concentration determined by comparison to the results obtained by running a known standard through the equipment, or in the case of an mass spectrometer (MS) detector, by comparison to a built-in library. The compound is identified on a chromatograph by its distinctive retention time - how long it takes to emerge from the GC - and is quantified by measuring the area under peak. Older equipment produces a paper chromatogram as output and does not store data long-term, whereas newer equipment typically requires the integrated use of a personal computer for data storage, management and output.

There are several detection technologies available and the five most appropriate for hazardous waste site characterization and remediation are described below:

mass spectrometer (MS): could be used for quantitative analysis of VOCs and SVOCs.(3) As the analyte enters the MS, it is ionized, typically by a 70 electron volt (ev) electron beam. Generally, the resulting fragmentation of the analyte produces a mass spectrum that represents the chemical structure of the analyte. The analyte is identified by comparing the resulting mass spectrum to a reference library. More specifically, the loss of an electron during ionization generates a charged molecular ion, usually with the same molecular weight as the analyte molecule. Excess energy from the beam further fragments the molecular ion to fragment (daughter) ions with lower mass to charge ratio. The positive ions and ion fragments produced by electron impact are attracted through the slits of the ion source and the mass analyzer. These ions are mass analyzed for differentiation according to their mass-to-charge ratios. The mass sorted ions are detected by an electron multiplier and the resulting signal is sent to a data system for processing.

  • The main advantage of an MS it that it can separate compounds that co-elute from the GC, providing interference-free detection and quantitation of each individual compound in a complex sample. Other detectors have difficulty identifying compounds within mixtures of similar compounds and can misidentify compounds when co-elution occurs.
  • An MS provides definitive compound identification and can determine the identity of a wide array of unknown compounds.(4) The other detectors can only identify the compounds that are in the quality control standards used each day to calibrate the equipment. Therefore, with detectors other than MS, the user must predetermine which compounds are present at the site and utilize standards containing those compounds.
  • An MS can detect compounds in the low part-per-billion (ppb) range; however the other detectors that can reach lower concentrations for some compounds.
  • An MS is a destructive technology, meaning it destroys the sample. However, an MS can characterize a wide variety of compounds (e.g. halogenated, aromatics, and hydrocarbons), so there is no need to use an additional detector to increase the range of applicability as with the other detectors.
  • An MS is the most complex detector, requiring a higher degree of operator expertise and maintenance than that required by the other detectors and therefore, there is a greater potential for equipment problems.
photoionization detector (PID): uses a special ultraviolet lamp to energize and ionize the separated compounds as they pass through the PID. The ions collect at positively charged electrodes where the change in current is measured and compared with standards for compound identification. The ultraviolet lamp energy can range from 9.5 to 11.7 eV, with 10.2 eV the most common. A 10.2 eV lamp can ionize compounds with ionization potentials below 10.2 eV, such as BTEX compounds and hexane. Chlorinated compounds with double bonds, such as trichloroethylene and tetrachloroethylene have lower ionization potentials and can be detected with the lower energy lamps. Chlorinated compounds with single bonds, such as methylene chloride and 1,1,1-trichloroethane require the higher energy lamps for ionization.
  • Field analysts report that a PID detector can be more sensitive and obtain lower detection limits than an MS. For example, a PID can detect BTEX in the low ppb to high ppt range.
  • A PID is responsive to aromatic and halogenated compounds.
  • PID is a non-destructive detector that can be used in series before other detectors. A PID is often coupled with an ECD.
  • The most commonly used lamp (10.2 eV) will report non-detect for the higher ionization potential compounds, generating false negatives when the compounds are in fact present.
  • identification and quantitation is limited to the compounds for which standards are run.
  • PID must be recalibrated more often than the FID.
flame ionization detector (FID): mixes the carrier gas containing the separated compounds with hydrogen in the presence of a flame. Hydrocarbons and other molecules which ionize in the flame are attracted to a collector electrode located to the side of the flame. The resulting electron current is amplified and converted into millivolts.
  • The FID also can detect more compounds than the PID. The FID is sensitive to virtually all compounds that contain hydrocarbons and that will burn, such as many aromatic and chlorinated VOCs, petroleum constituents, SVOCs, and PCBs. However, identification and quantitation are still limited to the compounds for which standards are run.
  • A FID can detect compounds in the low ppb to high ppt range.
  • FID is responsive to compounds with hydrogen - carbon bonds only. The FID will not respond to compounds without H-C bonds that are common in site investigations such as vinyl chloride and tetrachloroethylene.
  • FID is a destructive technology so no additional analysis can occur after it.
electron capture detector (ECD): contains radioactive nickel-63 that emits beta particles (electrons) which collide with the carrier gas. These collisions ionize the molecules to form a stable cloud of free electrons in the ECD cell. When an electronegative molecule such as a halogenated molecule enters the cell, it immediately combines with one of the free electrons, temporarily reducing the number of free electrons. This temporary reduction is measured by the detector. An ECD is highly sensitive to electronegative molecules such as halogenated compounds and those that contain nitrogen.
  • An ECD can detect highly halogenated compounds in the low ppb to ppt range - the more halogenated the compound the greater the sensitivity of the ECD.
  • The ECD is a non-destructive technology; however it is not used in series before other technologies due to the addition of electrons. An ECD often follows a PID to increase the range of compounds that can be identified.
  • Because the ECD contains radioactive material, users could be subject to licensing requirements and should check with the equipment vendor to determine the requirements in their particular state.
  • An ECD is only responsive to electrophilic compounds. For halogenated compounds, the sensitivity of the instrument is directly related to the degree of halogenation. For example, the ECD is orders of magnitude more sensitive to carbon tetrachloride than it is to vinyl chloride. Identification and quantitation is limited to the compounds for which standards are run.
  • The ECD is sensitive to water. Water negatively affects the condition of the Ni-63 foil that covers the detector and the foil must be reconditioned when its sensitivity diminishes.
electrolytic conductivity detector (ELCD): Organic compounds form combustion products as they are mixed with hydrogen gas over a nickel catalyst at 1,000 oC in a quartz tube furnace. The resulting change in electroytic conductivity is monitored by the ELCD. An ELCD is a halogen-specific detector that readily detects chlorinated pesticides, halogenated solvents, PCBs and dioxins.
  • The ELCD can detect halogenated compounds in the low ppb to ppt range.
  • An ELCD is uniformly selective so the degree of halogenation does not effect the sensitivity of the instrument to the compound as it does for the ECD.
  • ELCD is a destructive technology and cannot be used before another detector.
  • ELCD is limited to halogenated compounds only. Identification and quantitation is limited to the compounds for which standards are run.
  • ELCD typically requires more maintenance than PID, FID and ECD detectors.
Using two detectors in series can extend the range of compounds that can be detected in one analysis. PID and ECD detectors are commonly used in series. The other possible combination is PID followed by an ELCD.

Sample Preparation

The GC processes gaseous samples and therefore, water and soil samples must be prepared so as to drive the contaminants into gaseous phase. Descriptions of sample preparation for VOC and SVOC analysis are presented below. For contaminant mixtures containing both SVOC and VOC, two separate samples would need to be collected and analyzed with one undergoing the SVOC sample preparation process and the other undergoing the VOC process.

VOC Analysis: Soil samples first undergo an extraction procedure to move the contaminants into a liquid. Soil sample preparation can vary depending on the analyte concentration and the soil type. For low concentration samples (200 ppm) reagent grade water is often used to place the analytes into solution. Methanol is commonly used for samples with higher concentrations. One of two common techniques are used to move the contaminants from a liquid (either a water sample or the liquid from soil extraction) into the gaseous phase: static headspace or purge and trap. A third method for transfering sample contaminants from a liquid into the GC that shows promise for field application is solid phase microextraction (SPME). This technique is discussed further in the SVOC analysis section.

Static headspace: Static headspace requires minimal sample preparation. Static headspace relies on Henry's Law which states that the vapor pressure of the solute in the headspace is proportional to its mole fraction in solution. Therefore, analysis of the headspace determines the VOC concentration of a liquid sample without time consuming solvent extractions. Automated headspace samplers are available in which all samples are heated to the same temperature (typically in the range of 40 to 80oC) for the same amount of time (typically 10 to 30 minutes) to allow the sample to come to equilibrium. The headspace vial is pressurized and allowed to equilibrate. The headspace is vented into the sample loop where it is allowed to equilibrate again before it is drawn into the GC.
Purge and trap: In the purge and trap method, helium is bubbled through the sample at ambient temperature so the volatiles are transferred from the matrix to the vapor phase. The volatiles are then swept through a sorbent column where they are trapped. Then the column is heated and backflushed with helium to desorb the compounds which are transferred to the GC.
Comparison Between Static Headspace and Purge and Trap
  • Purge and trap is a dynamic process and it is a more efficient extraction technique for those VOCs which have a higher octanol/water partition coefficient, especially in soils with high organic matter content.
  • The purge and trap technique typically produces a significantly lower detection limit than static headspace because all of the sample is transferred to and is concentrated on the trap before analysis. Only a portion of the sample is transferred to the detection unit when static headspace is used.
  • The purge and trap method requires that the sample must be weighed and then transferred to a specially designed purge vessel, increasing the potential for VOC loss.
  • A purge and trap system requires decontamination between samples, increasing the potential for carryover contamination. To help prevent carryover contamination, samples with high contaminant concentrations should be diluted prior to introduction to the purge vessel. However, this introduces the potential for dilution errors.
  • Generally, the headspace technique affords a significantly higher throughput than a purge and trap system.
  • Purge and trap equipment is typically much larger than the equipment required for a headspace system.
SVOC Analysis: SVOC analysis in the field has not been widespread due to the traditional use of a carcinogenic solvent (methylene chloride) for the required liquid to liquid extraction procedures which creates hazardous waste, and also the need for the associated glassware and other equipment. If the liquid to liquid extraction is performed, the resulting liquid is typically injected into the GC using a special liquid injection port that flash vaporizes the liquid using high temperatures (typically 250-300oF). For soil samples the contaminants are extracted from the soil into a liquid prior to the liquid to liquid extraction.

There are two emerging extraction techniques that appear to be promising techniques for field use because they are rapid, use little or no solvent, simple, and inexpensive: solid-phase extraction (SPE) and solid phase microextraction (SPME). SPE is primarily limited to water samples, although it can be used as a cleanup technique for liquid extracts of solid samples. SPME has become popular in the last few years because it can be used for both VOCs and SVOCs and no solvent is required.

SPME requires that the sample is in a liquid or gaseous form, so soil samples must undergo an extraction procedure prior to SPME. SPME is a adsorption/desorption technique that uses a silica fiber coated with a polymer to adsorb organic analytes from the headspace of a liquid sample. The polymer coated fiber is then introduced to the GC injector where the analytes are thermally desorbed. It is important that the analyst allow the sample to come to equilibrium (usually 2-30 minutes) and maintain consistent sampling times to obtain reliable results. Selectivity can be altered by changing the type of polymer coating or the thickness of the coating to match the analytes of interest. In general a thick coating is better for VOCs and a thin coating for SVOCs. More information about SPME can be found at in the Supelco section.(5)

Thermal desorption of SVOCs is a technique to move the contaminants directly from a soil sample into the gaseous phase. A quantity of soil is placed in a chamber where it is heated to a high temperature, driving the SVOCs from the soil into the gas where it is drawn into the GC. Thermal desorption is convenient for field use because it is simple, rapid, and requires no solvent. However, the samples enter the GC at much higher temperatures than most other techniques and modifications are needed to account for this.

Independent Verification and Use in the Northeast:

Several different GC and GC/MS units have been evaluated in the EPA's Environmental Technology Verification (ETV) Program. The Technology Verification Statements for the evaluated units as well as more information about the ETV Program itself can be obtained at or by calling U.S. EPA Region I at (617) 575-CEIT. Three GC/MS technologies were evaluated as their own category under the Site Characterization and Monitoring Technologies Pilot, and two GC technologies and one GC/MS where evaluated under the Well-Head Monitoring - VOCs category within the same pilot.

GC technology has been used for site characterization or cleanup monitoring at over 25 Superfund sites, including several Department of Defense (DOD) and Department of Energy (DOE) facilities.(6) U.S. EPA Region I has used portable GCs, usually with PID and ECD detectors for "hot spot" identification at numerous sites since the 1980's and reports a throughput of up to 50 samples per day (includes QA/QC sample analysis). EPA Region I also uses portable GCs for removal verification. EPA Region I has also used portable GC/MS technology at several sites in New England.

Some of Northeast states, notably Connecticut, Massachusetts, New York, and Vermont, have successfully used GC technology, with PID, FID, ECD and ELCD detectors, during site characterization and/or remediation. Connecticut has a state-certified mobile laboratory that uses GC/MS. Massachusetts has also used portable GC/MS at three DOD sites, including Hanscom Air Force Base (HAFB). At HAFB, screening analysis using a GC/MS was done in the field and quantitative GC/MS analysis was performed in an on-site mobile laboratory trailer. A detailed case study of the HAFB was prepared by the U.S. EPA (EPA-542-R-98-006) and is available at in the Site Characterization section.


The TRC has determined that, if used properly, field portable GC technology combined with an appropriate detector, can provide useful data that should improve site characterization and/or cleanup verification. The intended use of the data and data quality objectives (DQOs) must be determined prior to the field event and agreed to by the appropriate regulatory authority. The TRC recommends the following items to improve or insure product performance; however, users should recognize that each particular GC - detector combination might have additional requirements:

  1. Personnel who use field portable GC technology must be qualified and receive formal training on the particular instrument. Operators with an analytical chemistry background can often be trained to use the instrument in one or two days, with GC/MS requiring longer. Operators without an analytical chemistry background would need more training. GC vendors typically offer training, either included in the instrument purchase price or for a fee. Users should carefully follow the manufacturers instructions. At least one state, New York, requires that the resume of the Field Analyst, including relevant experience and education, be submitted for review by the state's Quality Assurance Section prior to the sampling event.
  2. All samples, particularly soil and water samples must be collected and handled following standard procedures to reduce the loss of volatile components and to promote consistency and comparability of results.
  3. To ensure data quality and comparability, all samples, including QA/QC standards should be in thermal equilibrium at a similar temperature before analysis.
  4. QA/QC requirements vary with different DQOs and regulatory authorities and should be agreed upon prior to the field event. Users are expected to record the results of the QA/QC sample analyses and evaluate them daily to ensure that the analyses and QA/QC checks meet the criteria established in the vendor literature and the project DQOs. Generally, the following types of QA/QC measures are required, at a minimum to obtain useful data for making regulatory determinations:(7)
    1. An initial three-point external standard should be performed.(8)
    2. A mid-point calibration should be performed at every 10 samples, at a minimum or at least once per day if less than 10 samples are analyzed.(9)
    3. An instrument blank should be run after each standard calibration, and also after the analysis of a highly contaminated sample to determine if residual contamination exists in the equipment.(10)
    4. Duplicate samples should be analyzed (with the field GC) at a minimum frequency of 1 per 10 or 1 per 20 (depending on the DQOs) or once per day, whichever is more frequent. Duplicates are two portions of the same sample that have been prepared together, and then split and analyzed in the same manner.
    5. A confirmatory sample should be collected and prepared in the same manner as a duplicate sample, and sent for laboratory analysis at a minimum frequency of 1 per 10 or once per day, whichever is more frequent.
    6. When sample preparation is performed using non-dedicated equipment, a method blank should be analyzed once a day or every 10 samples, whichever is more frequent to evaluate decontamination techniques.
    7. For soil samples, matrix spike/matrix spike duplicate samples should be analyzed to check for extraction efficiency. Percent recoveries are calculated and compared to each other by calculating the relevant percent difference (RPD).
  5. The presence of certain compounds can interfere with the analysis by PID, FID, ECD and ELCD detectors. Multicomponent mixtures interfere with individual analytes due to co-elution problems. For example, mixtures of petroleum products with BTEX or PAH; PCBs with chlorinated pesticides; and toxaphene with chlorinated pesticides can have compounds that co-elute, causing PID, FID, ECD and/or ELCD detectors to misidentify the compounds present. Using a GC/MS can mitigate these problems.


The NEWMOA Technology Review Committee has issued this Advisory Opinion on this 29th day of November, 2000.

Christine Lacas, Connecticut DEP

Paul Kulpa, Rhode Island DEM

For More Information Please Contact:
In Connecticut:
Christine Lacas
Department of Environmental Protection
Bureau of Water Management
79 Elm Street
Hartford, CT 06106
(860) 424-3766
In Maine:
Mark Hyland
Department of Environmental Protection
Bureau of Remediation and Waste Management
17 State House Station
Augusta, ME 04333
(207) 287-7673
In Massachusetts:
Dorothy Allen
Department of Environmental Protection
Bureau of Waste Site Cleanup
One Winter Street
Boston, MA 02108
(617) 292-5795
In New Hampshire:
Robert Minicucci
Department of Environmental Services
Waste Management Division
6 Hazen Drive
Concord, NH 03301
(603) 271-2941
In New York:
James Harrington
Department of Environmental Conservation
Division of Environmental Remediation
50 Wolf Road
Albany, NY 12233
(518) 457-0337
In Rhode Island:
Paul Kulpa
Department of Environmental Management
Office of Waste Management
235 Promenade Street
Providence, RI 02908
(401) 222-2797
In Vermont:
Richard Spiese
Department of Environmental Conservation
Waste Management Division
103 South Main Street
Waterbury, VT 05671
(802) 241-3888
William Cass
129 Portland Street, 6th Floor
Boston, MA 02114
(617) 367-8558, ext. 301
At EPA New England:
Carol Kilbride
Center for Environmental Industry and Technology
One Congress Street, Suite 1100
Boston, MA 02114
(617) 918-1831

1. In this document, the Northeast states are: Connecticut, Maine, Massachusetts, New Hampshire, New York, Rhode Island and Vermont.

2. provided 10 percent of samples are sent to a fixed laboratory for confirmatory analysis and appropriate quality assurance/quality control (QA/QC) is performed, including a correlation study.

3. Dioxin analysis requires the use of a high resolution MS which is currently not practical for field use.

4. Appropriate QA/QC measures and analysis is required for definitive identification.

5. Mention of any company or product name should not be considered an endorsement by NEWMOA, NEWMOA member states, or the U.S. EPA.

6. U.S. EPA, Field Analytical and Site Characterization Technologies, Summary of Applications, EPA-542-R-97-011, November 1997.

7. Less stringent QA/QC could be appropriate for field screening and/or determining which samples are best to send to a fixed laboratory - check with your regulatory authority.

8. New York specifies that the correlation co-efficient is 0.95.

9. New York specifies that the relative percent difference (RPD) is 30 percent.

10. New York specifies that the peak area for each target compound should be less than half the area of the reported detection limit.