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Ohmicron Environmental Diagnostics, Inc.-PCB RaPID Assa-(PCBs in Water and Soil)

Final Decision to Certify Hazardous Waste Environmental Technology

The following is excerpted from:

Published Weekly by the Office of Administrative Law
Register 94, No. 35-Z
September 2, 1994
pp 1395-1397

The California Environmental Protection Agency, Department of Toxic Substances Control (Department) 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

PCB RaPID Assay®, an enzyme immunoassay for fast,
semiquantitative field measurements of
polychlorinated biphenyls in water and soil.

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 the Department to certify the performance of hazardous waste environmental technologies.

DTSC’s notice to certify was published in the California Regulatory Notice Register Volume 94, No. 35-Z. The DTSC’s final certification shall be effective from October 3, 1994 to October 3, 1997.

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
301 Capitol Mall, 1st Floor
Sacramento, California 95812-0806
(916) 322-3670

A description of the technology to be certified, the final certification statement and the certification limitations for the technology follows:

Ohmicron Environmental Diagnostics, Inc.
PCB RaPID Assay®
(PCBs in Water and Soil)

Technology Description

The Ohmicron RaPID Assay® System for PCBs uses enzyme immunoassay technology. It differs from other systems in that polyclonal antibodies are supplied attached to magnetic particles. Competitive ELISA immunochemistry is employed. PCBs in water are assayed after addition of an equal amount of methanol to the sample; for soils, the system uses methanol extraction. After color development, readout is by a small, automated laboratory photometer or a hand-held, microprocessor-equipped, battery-operated photometer for field use. Alternatively, standard laboratory photometers can be used.

Certification Statement

Under the authority of Section 25200.1.5 of the California Health and Safety Code, the Department hereby certifies the PCB RaPID Assay® (PCBs in Water and Soil) manufactured by Ohmicron Environmental Diagnostics, Inc. as a Measurement Technology. The test kit consists of a semi-quantitative immunoassay system for the detection of PCBs, as Aroclors, in methanol mixtures of water and methanol extracts of soil. Provided that the immunoassay is used properly, detection of Aroclor 1254 is 0.5 to 10 ppb in water and 0.5 to 10 ppm in soil; ranges can be extended upward by dilution of the methanol extracts. For other Aroclors, correction factors apply and detection levels are higher. Quantitative readings about a selected target level are obtained in a microprocessor-equipped, hand-held, battery-operated photometer or a compact table top photometer supplied by the manufacturer, or a standard laboratory photometer. The calibration is not biased, but the user is instructed to select target levels so as to regulate the possibility of false negative results. The Department’s findings are described in greater detail in an evaluation report.

Limitations of Certification

The Department makes no express of implied warranties as to the performance of the manufacturer’s product or equipment. The Department has not conducted any bench or field tests to confirm the manufacturer’s performance data. Nor does the Department 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.

The Department 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.

Specific Conditions

Differences in the types of Aroclor and changes in PCB composition during long-term field exposure (weathering) can cause positive or negative errors in the immunoassay results of one order of magnitude or more. Users should evaluate these factors before attempting to quantify results. In soil studies, users should be encouraged to prepare soil matrix spikes and vary extraction times to establish local soil extraction efficiency and to evaluate interferences (matrix effects). We recommend that Aroclor-spiked soil samples be allowed to age for a two-week period for a more representative evaluation of extraction efficiencies.

Although precision of the assay is acceptable, in view of the above, users should be discouraged to report results with more than two significant figures unless this is specifically required in a Quality Assurance Plan to facilitate statistical treatment of the data. Ohmicron should continue to support and participate in evaluations of the RaPID Assay for PCBs by independent agencies and furnish reports to the Department as they become available.

Basis for Certification

The documentation submitted by the manufacturer is listed in the evaluation report on which this certification is based. The manufacturer has asserted that certain materials contain proprietary information and therefore should not be subject to public disclosure.

Recommended Applications of the Test System

The immunoassay is for the semiquantitative determination of PCBs in terms of commercial mixtures of PCBs (Aroclor 1254) that has been used in the design and calibration of the assay. Conversion factors are applied to the results for Aroclors to which the assay responds differently. Unknown PCB mixtures need to be characterized by a reference method and a conversion factor needs to be determined which reflects the immunoassay response of that mixture relative to the response of Aroclor 1254. Without such an adjustment, results can be either high or low, depending on the affinity for the assay’s antibodies of an unknown PCB mixture. A semiquantitative determination will provide a response, interpreted as either positive or negative, at one or several predetermined detection or target levels. Target levels are usually chose to have relevance to a specific situation.

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 for PCB-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 (identification and quantification, i.e., EPA Methods 8080 or 8081) applied predominantly to positive results. We recommend that minimum quality control should include method blanks and duplicates at 5 percent, or one per batch or per matrix, whichever is the more frequent, in addition to the samples required for confirmation. The use of proficiency evaluation and spiked samples should depend on project-specific needs.

We recommend gas-chromatographic U.S. EPA Methods 8080 or 8081 for establishing or confirming the types and concentrations of Aroclor(s).

“Screening” and Preliminary Site Investigations-

The immunoassay can assist in preliminary site investigations (“Phase I”), if there are compelling historical data to indicate a potential for the presence of PCBs. If used on samples of largely unknown composition, without prior characterization by an approved, 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. A margin of error (above the stated detection level) should be allowed for those PCBs that may show a lower response than those for which the assay has been calibrated.

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

(a) For the detection of PCB contamination 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.

(b) 10 to 20 percent of results which are above the detection level but below the target or 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; and

(c) 5 to 10% of all negative results, but no less than one result from each site or suspect area, should be confirmed.

If appropriate protocols are followed, the immunoassay can be used to great advantage to classify contaminated soils as to low, medium, or high contamination and to determine which samples would provide the most information from laboratory analysis.

Site Investigations and Remedial Actions-Here the testing is expected to proceed under a site-specific Quality Assurance Project Plan (QAPP). Immunoassay and other field measurements will be “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. After such initial characterization, the immunoassay can be used in the comprehensive mapping of the site with respect to identified contaminant(s) to which the immunoassay responds. The 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 such a need is 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

The Department’s Certification is based on the technology’s performance and by itself does not change the regulatory status of PCB 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, the Department’s findings should contribute to a consideration of this technology in regulated activities, depending on each regulated program’s objectives and constraints.

State certification does not imply certification by the U.S. Government for use at federal superfund sites and other facilities under the jurisdiction of the U.S. Government for which state authorization for administrative oversight has not been granted. Under state implementation of the U.S. Resource Conservation and Recovery Act (RCRA), Treatment, Storage, and Disposal Facilities may contact state permitting agencies for use of the immunoassay for operational monitoring as part of a Waste Analysis Plan (WAP).

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 the Department as required by the law under which this Certification is granted.

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