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Ohmicron Environmental Diagnostics, Inc-PAH RaPID ASSAY-(Immunoassay for Polynucleated Aromatic Hydrocarbons in Soil and Water)

Final Decision to Certify Hazardous Waste Environmental Technology

The following is excerpted from:

Published Weekly by the Office of Administrative Law
Register 96, No. 30-Z
July 26, 1996
pp 1422-1425

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 listed below:

Ohmicron Environmental Diagnostics, Inc.
375 Pheasant Run
Newtown, PA 18940

(Immunoassay for Polynucleated Aromatic Hydrocarbons in Soil and Water)

Chapter 412, Statutes of 1993, Section 25200.1.5., Health and Safety Code, enacted by Assembly Bill 2060 (Weggeland) and effective January 1, 1994 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 public health and the environment.

By accepting certification, the manufacturer assumes, for the duration of certification, responsibility for maintaining the quality of the manufacturered 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 in the California Regulatory Notice Register Volume 96, No. 30-Z. The DTSC’s final certification shall be effective from August 26, 1996 to August 26, 1999.

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

California Environmental Protection Agency
Department of Toxic Substances Control
Office of Pollution Prevention and Technology Development
P.O. Box 806
Sacramento, California 95812-0806

The final certification statement and the certification limitations for the technology follows:

Ohmicron Environmental Diagnostics, Inc.
(Immunoassay for Polynucleated Aromatic Hydrocarbons in Soil and Water)

Certification Statement and Technology Specifications

Under the authority of Section 25200.1.5 of the California Health and Safety Code, the Department hereby amends the previous certification of the PAH RaPID Assay® manufactured by Ohmicron Environmental Diagnostics as a Measurement Technology for the examination of soils. By amendment to the Notice of Intent, certification is extended to the use of the assay in the examination of water samples. Amendment is on the basis of additional data received. The technology is based on the principle of enzyme-linked immunosorbent assay (ELISA). It differs from other systems in that polyclonal antibodies are bound to micron-sized superparamagnetic particles. Water samples are tested directly. Soil samples are extracted with a modified methanol solution using the Ohmicron RaPID Prep PAHs Sample Extraction Kit. The assay is carried out with the diluted 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 portable field or a laboratory photometer.

While the individual PAHs respond differently to the assay, contamination of the soil is indicated in terms of a manufacturer-supplied calibration standard which contains phenanthrene. The assay responds with different sensitivities to a number of PAHs, including several known carcinogens. Three concentration levels of calibrator are provided with the test kit.

The assay is semi-quantitative in that it is intended for the detection and quantification of PAHs in terms of the supplied calibrator levels. The normal testing range in water is from 0.93 to 66.5 ppb as phenanthrene. Samples containing gross particulates should be filtered. The assay sensitivity in soil is 0.2 ppm in terms of phenanthrene, normal operating range is from 0.2 to 5 ppm. Higher concentrations can be assayed after diluting the extract. The assay does not respondto lower aromatic hydrocarbons including naphthalene. Humic acids are a known possible interfering agent. Not all matrix effects may yet be known, and confirmatory analysis by approved methods such as U.S. EPA Method is necessary to identify and quantify individual PAH compounds, to confirm positive results in site characterizations, and to decide on site closure after cleanup.

Soils with up to 20 to 25 percent water content can be tested; extraction efficiency is reduced at soil water content over 30 percent. 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 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

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 polynucleated aromatic hydrocarbons (PAHs) in soil and water. PAH measurements also serve as an indicator for the presence of heavy petroleum fuels and tars which contain varying concentrations of these compounds. The RaPID PAH system is a semiquantitative assay which responds to high-molecular aromatics and some related compounds. It is initially calibrated with a pure solution of phenanthrene as described above. Through appropriate recalibration, its response can be related to concentrations of actual mixtures present at certain sites, although calibration against a laboratory reference method such as U.S. EPA Method 8310 is a more appropriate approach. Immunoassay testing is no substitute for those complex scientific methods which more specifically allow to determine potential health and environmental risks associated with heavy petroleum hydrocarbons.

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 is instructed to adopt a higher target 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.

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 one per ten-sample 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.

“Screening” and “Preliminary Site Investigations”

The immunoassay can assist in site investigations, if there are compelling historical data to indicate the presence of PAHs (e.g., spills of heavy oils, handling or processing of petroleum fuels, coal gas plants, and other sites contaminated with products of incomplete combustion). 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.

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

  1. For the delineation of contamination with PAH or heavy petroleum fuels in a coherent mass of soil, the required frequency of confirmation by an approved method resulting in identification and quantification is at least 10 percent of the samples testing positive at the target or action level applicable at the site. In the event that fewer than ten samples meet these criteria, at least one positive sample shall be confirmed. Higher rates of confirmation apply if there is a potential for chemical interferences.
  2. Ten to twenty percent of results which are above the detection level but below the targetor action level should be confirmed by an approved, fully quantitative method, except that a higher rate of confirmation may be necessary if the results are to be used in health risk assessments.
  3. Five to ten percent of all negative results, but no less than one result from each site or suspect area, 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 approved, 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

DTSC’s certification does not change the regulatory status of PAH 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: October 31, 1996