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COMPARISON OF IMMUNOASSAY AND GAS CHROMATOGRAPHY/MASS SPECTROMETRY FOR MEASUREMENT OF POLYCYCLIC AROMATIC HYDROCARBONS IN CONTAMINATED SOIL
Chuang, J. C., Y. L. Chou, N. Junod, J. K. Finegold, N. K. Wilson, AND J M. Van Emon. COMPARISON OF IMMUNOASSAY AND GAS CHROMATOGRAPHY/MASS SPECTROMETRY FOR MEASUREMENT OF POLYCYCLIC AROMATIC HYDROCARBONS IN CONTAMINATED SOIL. ANALYTICA CHIMICA ACTA 486(1):31-39, (2003).
More cost-effective field screening and monitoring methods will be provided to increase the amount of information available concerning the location, source, and concentration of pollutants. Rapid and sensitive immunoassays such as enzyme-linked immunosorbent assays (ELISAs) to monitor remediation and cleanup activities at Superfund sites will be developed. Each new method will be tested on real-world samples from monitoring studies. Field studies will be conducted when time and resources permit. The feasibility and application of immunosensors to provide field analytical methods for the dynamic monitoring of hazardous substances of interest to the EPA will also be investigated. Concern has been expressed for the potential exposure of individuals to toxic compounds who live near hazardous waste sites or who may become exposed through other means. Thus, the development of methods for measuring biomarkers for human exposure assessment studies is also addressed.
During the remainder of the Task several projects will be undertaken including:
- Complete the development and evaluation of bioanalytical methods for dioxin and related compounds
- Perform dioxin immunoassay analysis on samples from a dioxin SITE demonstration
- Comparison of an ELISA with gas chromatography (GC) for monitoring polychlorinated biphenyls (PCBs) in soils/sediments collected from a Superfund field demonstration
- Survey of bioanalytical methods and sensor technologies for environmental monitoring
- Development of immunoaffinity chromatography sample preparations for PCBs
- Preparation of standard operating procedures (SOPs) for each bioanalytical method developed
- Conduct yearly research meeting
- Conduct survey of high priority chemicals at National Priorities List (NPL) sites for bioanalysis suitability
- Develop new bioanalytical methods for hazardous compounds of public concern
- Perform PCP immunoassay analysis on soil and sediment samples from a Superfund site and compare with GC data
- Preparation of fact sheets and journal articles
Polycyclic aromatic hydrocarbons (PAHs) are frequently encountered in the environment and may pose health concerns due to their carcinogenicity. A commercial enzyme-linked immunosorbent assay (ELISA), was evaluated as a screening method for monitoring PAHs at contaminated sites. The ELISA was a Carcinogenic PAH (C-PAH) RaPID@ assay testing kit that cross-reacts with several PAHs and utilizes benzo[a]pyrene (BaP) as a calibrator. Soil samples were extracted with 50% acetone in dichloromethane (DCM) for analysis by ELISA and gas chromatography/mass spectrometry (GC/MS). The overall method precision was within plus/minus 30% for ELISA and within plus/minus 20% for GC/MS. Recovery data for spiked soils ranged from 46 to 140% for BaP as determined by ELISA. Recoveries of the GC/MS surrogate standards, 2-fluorobiphenyl and chrysene, were greater than 70%. The GC/MS procedure detected a total of 19 priority PAHs (2- to 6-ring PAHs) including seven probable human carcinogens (4- to 6-ring B2-PAHs). The ELISA results were compared to GC/MS summation results for the total 19 target PAHs as well as for the subset of the seven B2-PAH compounds. For all soil samples, the PAH concentrations derived from ELISA were greater than the sum of B2 PAH concentrations obtained by GC/MS. ELISA determinations were also frequently greater than the results obtained by GC/MS for the total 19 PAH compounds. This discrepancy can be expected, since the ELISA is a screening assay for the detection of several related PAHs while the GC/MS procedure detects priority PAH compounds. Thus, only a subset of PAHs (e.g., 19 PAHs) in the soil samples were measured by GC/MS while additional PAHs, including alkylated PAHs, and PAH derivatives have been demonstrated to be cross reactive in the C-PAH ELISA. Results of paired tests show that the PAH data from ELISA and GC/MS methods are significantly different (p <0.001), but highly correlated. The ELISA data had a strong positive relationship with the GC/MS summation data for the B2 PAHs as well as for the 19 PAHs targeted by the GC/MS method. Results indicate that the ELISA may be useful as a broad screen for monitoring PAHs in environmental samples.
This work was funded by EPA contracts 68-C5-0075 and 68-D-99-011. This paper has been reviewed in accordance with the US Environmental Protection Agency's peer and administrative review policies and approved for publication. Mention of trade names and commercial products does not constitute endorsement or recommendation for use.