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Millipore Corporation-EnviroGard-Petroleum Fuel in Soil Test Kit (Total BTEX)

Final Decision to Certify Hazardous Waste Environmental Technology

The following is excerpted from:

Published Weekly by the Office of Administrative Law
Register 96, No. 7-Z
February 16, 1996
pp 253-256

The California Environmental Protection Agency, Department of Toxic Substances Control (DTSC) has made a final decision to certify the following company’s hazardous waste environmental technology:

Millipore Corporation
80 Ashby Road
Bedford, Massachusetts 01730

EnviroGardTM Petroleum Fuel in Soil Test Kit (Total BTEX).

Chapter 412, Statutes of 1993, Section 25200.1.5, Health and Safety Code, enacted by Assembly Bill 2060 (AB 2060 by Assemblyman Ted Weggeland), authorizes DTSC to certify the performance of hazardous waste environmental technologies. Only technologies that are determined not to pose a significant potential hazard to the public health and safety or to the environment when used under specified operating conditions and which can be operated without specialized training and with minimal maintenance may be certified. Incineration technologies are explicitly excluded from the certification program.

The purpose of the certification program is to provide an in-depth, independent review of technologies at the manufacturer’s level to facilitate regulatory and end-user acceptance and to promote and foster growth of California’s environmental technology industry.

DTSC makes no express or implied warranties as to the performance of the manufacturer’s product or equipment. The end-user is solely responsible for complying with the applicable federal, state, and local regulatory requirements. Certification does not limit DTSC’s authority to require additional measures for protection of the public health and the environment.

By accepting certification, the manufacturer assumes, for the duration of certification, responsibility for maintaining the quality of the manufactured equipment and materials at a level equal or better than was provided to obtain certification and agrees to be subject to quality monitoring by DTSC as required by the statute under which certification is granted.

DTSC’s notice to certify was published on February 16, 1996 in the California Regulatory Notice Register Volume 96, No. 7-Z, pages 253-256. DTSC’s final certification shall be effective from March 18, 1996 to March 18, 1999.

Additional information supporting DTSC’s final certification decision is available from:

California Environmental Protection Agency
Department of Toxic Substances Control
Office of Pollution Prevention and Technology Development
P.O. Box 806, 301 Capitol Mall, 1st Floor
Sacramento, CA 95812-0806
(916) 322-3670

A description of the technology to be certified, the certification statement, and the certification limitations for the technology of the company listed above follows. 

Millipore Corporation
EnviroGardTM Petroleum Fuel in Soil Test Kit (Total BTEX)
(Total Benzene, Toluene, Ethylbenzene, and Xylenes in Soil)

Certification Statement and Technology Specifications

Under the authority of Section 25200.1.5 of the California Health and Safety Code, DTSC hereby certifies the EnviroGardTM Petroleum Fuel in Soil Test Kit (Total BTEX) manufactured by Millipore Corporation as a Measurement Technology. The technology is based on the principle of enzyme-linked immunosorbent assay (ELISA). In the Millipore assay, polyclonal antibodies are bound to the interior walls of polystyrene test tubes. Soil samples are extracted with methanol using the EnviroGardTM Field Soil Extraction Kit. The assay is carried out with a diluted methanol extract of the soil. After the analyte and a competing enzyme conjugate have been allowed to bind to the antibody and excess reagents have been removed, a enzyme-mediated color reaction is initiated and the intensity of the resulting yellow color determined in a photometer.

The antibody used in this assay is the same as in the Manufacturer’s TPH assay, but it is calibrated using standards consisting of equal parts of benzene, toluene, ethylbenzene, o-, m-, and p-xylene. The strongest response in the assay is from m-xylene; the response from benzene is quite weak (2% of the response of the BTEX calibrator). The assay does not respond to n-alkanes. Non-BTEX compounds that show a positive reaction in the assay are other methylbenzenes, naphthalene, acenaphthylene, acenaphthene, and to a small extent the higher polynucleated aromatic hydrocarbons. The assay detects gasoline by virtue of its content of responsive BTEX and chemically related components. Compared to the BTEX calibrator or gasoline, the detection level for diesel fuel is somewhat higher. For results to be expressed in terms of a specific petroleum fuel, calibration can be performed using such a product; calibrations may be related to each other by the use of appropriate conversion factors. Four concentration levels of standard calibrator are provided with the test kit.

The assay is semi-quantitative in that it is intended for the detection and quantification of petroleum fuels in relation to the supplied BTEX calibrator levels of 2, 10, 50, and 300 ppm, or intermediate levels available from the manufacturer. Higher concentrations can be assayed after diluting the extract.

While the known cross-reactants do not interfere with the assay’s ability to detect petroleum fuels and may even enhance it, not all matrix effects may yet be known, and confirmatory analysis by approved methods such as U.S. EPA Method 8020/8021 or 8240/8260 is necessary to identify and quantify individual BTEX compounds, to confirm positive results in site characterizations, and to decide on site closure after cleanup. The assay should not be considered a test for the presence of benzene except by indicating petroleum fuels that are known or can be assumed to contain benzene. The assay is not recommended for the detection of polynucleated aromatic hydrocarbons (PAHs).

The assay is designed to have a slight positive bias which reduces the probability of false negative results at the expense of obtaining false positive results in the order of 7 to 15%, depending on the site; bias is determined by the relationship between calibration and target levels selected. Soils with up to 20 to 25 percent water content can be tested; extraction efficiency is reduced at 30% water content or higher.

Great care is required in soil sampling and sample handling to reduce losses of the volatile BTEX compounds. As with similar assays, certain temperature controls are required for reagent storage and for carrying out the assay. The assay should be used only by trained individuals to reduce operator-caused variability.

Limitations of Certification

DTSC makes no express or implied warranties as to the performance of the manufacturer’s product or equipment. DTSC has not conducted any bench or field tests to confirm the manufacturer’s performance data. Nor does DTSC warrant that the manufacturer’s product or equipment is free from any defects in workmanship or material caused by negligence, misuse, accident, or other causes.

DTSC believes, however, that the manufacturer’s product or equipment can achieve performance levels set out in this Certification. Said belief is based on a review of the data submitted by the manufacturer and other information, and is based on the use of the product in accordance with the manufacturer’s specifications.

This Certification is issued as part of a pilot project to expedite the California Environmental Technology Certification Program. As a result, this Certification is subject to the conditions set out in the regulations to-be-developed, such as the duration of the Certification, the continued monitoring and oversight requirements, and the procedures for certification amendments, including decertification.

By accepting this Certification, the manufacturer assumes, for the duration of the Certification, responsibility for maintaining the quality of the manufactured materials and equipment at a level equal or better than was provided to obtain this Certification and agrees to be subject to quality monitoring by DTSC as required by the law under which this Certification is granted.

Specific Conditions

  1. Product Insert shall state that the product is not intended for the detection of benzene other than through the detection of petroleum fuels which are known or can be assumed to contain benzene.

  2. User instructions need to include indication of the need for training by Millipore personnel or another trained user. Materials Safety Data Sheets must be distributed such that they are available to users in both field and laboratory settings.

  3. Through updates of user guides, Manufacturer shall inform the user of interferences and matrix effects which potentially affect the testing results as they become known to the Manufacturer.

Basis for Certification

This certification is based on the evaluation of documents provided by the manufacturer and on independent evaluations which support performance claims consistent with this certification. A listing of these documents is contained in the evaluation report. The manufacturer has declared that certain submitted materials contain proprietary information and should not be subject to public disclosure.

Recommended Applications

The assay is for the semiquantitative determination of petroleum fuels in soil in terms of the assay’s BTEX calibrator. “BTEX” is a term of convenience for the sum of benzene, toluene, ethylbenzene, and xylenes as determined by compound-specific analyses. “BTEX” measurements are often used as an indicator for the presence of petroleum fuels which contain varying concentrations of these compounds. The EnviroGard system is a semiquantitative assay which responds to low-molecular aromatics and some chemically related compounds. It is initially calibrated with a pure mixture of BTEX as described above. Through appropriate recalibration, its response can be related to concentrations of specific petroleum fuels, resulting in a predictable relationship between immunoassay and reference methods for these products. In the case of immunoassays for petroleum fuels (as BTEX or as Total Petroleum Hydrocarbons, TPH), the correlation between immunoassay results and laboratory reference testing results can change for three reasons:

  1. Petroleum fuels are reformulated from time to time by geographic region, by season, or on a national scale to meet air pollution or other requirements. Reformulation may include the addition of non-hydrocarbon chemicals which may or may not react in the assay.

  2. Laboratory reference methods for total petroleum hydrocarbons may be revised, resulting in an altered response relative to an immunoassay and a need to update the assay’s calibration or interpretation.

  3. In water and soil, the composition of petroleum products changes as a result of solution, volatilization, chemical oxidation, and biodegradation. Especially benzene, like the lower alkanes, may be lost through volatilization. In the presence of water, benzene is lost by solubilization; lower aromatics, like the linear alkanes, are potentially lost by biodegradation.

Therefore, in both site characterizations and remediations, BTEX-specific immunoassays may need recalibration by parallel testing with an applicable regulatory laboratory method and determination of an appropriate conversion factor. Without such adjustment, results can be either high or low, depending on the affinity of the assay’s antibodies for the target mixture.

Semiquantitative determinations will provide responses, interpreted as either positive or negative, at one or several predetermined detection or target levels. Target levels are usually chosen to have relevance to a specific situation.

In each application of the assay, the probability of false negative and false positive results disclosed by the manufacturer should be considered. To lower the false negative rate (at the expense of raising the false positive rate), the user can adopt a higher detection level without otherwise changing the test. This may be desirable in site investigations, where the false negative rate is critical and kept as low as is appropriate for the decision(s) to be made. In site remediations, however, lowering the false positive rate is important, and a lower target level may be adopted for the same assay.

Independent validation of immunoassay results is also important in the use of testing kits for petroleum fuels, whether in terms of BTEX or TPH, because the human toxicity of the chemical species of the mixtures referred to as “BTEX” or “TPH” does not necessarily parallel their reactivity in an immunoassay. This particularly applies to benzene which, in contrast to its human toxicity, reacts only weakly in the immunoassay. Therefore, the immunoassay testing is no substitute for those complex scientific methods which more specifically allow to determine potential health and environmental risks associated with petroleum hydrocarbons.

A comprehensive process of developing data quality objectives (DQO) was published by U.S. EPA under the U.S. Superfund program. It provides guidance for analytical method QA/QC as applied to field investigations of contaminated soils. The process is intended for site-specific sampling plans. Here the immunoassay would generally qualify as a level 2 (field analysis) method, subject to confirmation by a level 3 method (confirmation and quantitation) applied predominantly to positive results. We recommend that minimum quality control should include a method blank and duplicates at five percent, or one per batch or per matrix, whichever is more frequent, in addition to the samples required for confirmation. The use of proficiency evaluation and spiked samples depends on project-specific needs.

U.S. EPA Method 602, and SW-846 Methods 8020/8021 (packed and capillary column gas chromatography), and 8240/8260 (packed and capillary column gas chromatography/mass spectrometry) are approved for the confirmation of BTEX identification and quantitation. The LUFT TPH Method, a modification of U.S. EPA Method 8015 (gas chromatography with flame-ionization detector), is approved for Leaking Underground Fuel Tank (LUFT) investigations in California.

“Screening” and “Preliminary Site Investigations”

The immunoassay can assist in site investigations, if there are compelling historical data to indicate the presence of petroleum fuels (e.g., oil spill, handling or processing of petroleum fuels). If used on samples of largely unknown composition, without prior characterization by a fully qualitative and quantitative laboratory method, confirmatory analysis is needed for every positive immunoassay result. No negative determinations can be made without taking into account the specificity of the assay and its possible susceptibility to interferences and matrix effects. Benzene poses a special problem, because it reacts only weakly in the immunoassay, but is also one of the most volatile components, and the most water soluble and most toxic of many petroleum products.

In the absence of other regulations and guidelines, we recommend that assay results be confirmed in the following manner:

  1. For the delination of petroleum fuel contamination in a coherent mass of soil, the required frequency of confirmation by an approved method resulting in identification and quantification should be one for every ten, or a fraction thereof, samples testing positive at the target or action level applicable at the site.

  2. One of every ten, or fraction thereof, negative results should be confirmed.

Site Investigations and Remedial Actions

For remedial investigations or RCRA facility investigations, testing usually proceeds under a site-specific Quality Assurance Project Plan (QAPP). Immunoassay and other field measurements are “bracketed” in time and space by qualitative and fully quantitative analyses. Generally, a site is first characterized by the use of approves, fully qualitative and quantitative analytical methods as to the nature and level of contamination in key sampling locations and as to the presence of substances that may interfere with the use of the immunoassay. The immunoassay can then be used in the comprehensive mapping of the site with respect to identified contaminant(s) to which the immunoassay responds. A specified percentage of samples that would be confirmed by another approved, fully quantitative method would be as stipulated in the QAPP; the project manager could call for additional confirmatory testing if indicated in the course of the investigation. During site cleanup, the QAPP would provide for use of the immunoassay to monitor progress. Confirmatory laboratory testing would occur before a decision on site closure is made.

Regulatory Implications

This immunoassay has been accepted as a Draft Method by the U.S. EPA Office of Solid Waste as Method 4031 (SW-846 Manual of Methods). DTSC’s certification does not change the regulatory status of petroleum fuel or BTEX testing; it should, however, facilitate and encourage the acceptance of this technology where a project’s data quality objectives can be met by its use. To this end, DTSC’s findings should contribute to a consideration of this technology in regulated activities, depending on each regulated program’s objectives and constraints. State-regulated disposal facilities may contact state permitting officers for use of the immunoassay for operational monitoring. Other local and state government permitting authorities may take this certification under consideration when making their permitting decisions. Other project leaders may consider using this assay if a project’s data quality objectives can be met by its use.

For more information, contact us at:

Department of Toxic Substances Control
Office of Pollution Prevention and Technology Development
P.O. Box 806
Sacramento, California 95812-0806
Phone: (916) 322-3670
Fax: (916) 327-4494

File last updated: August 28, 1997