Modern Water: A00205: PAH in water by immunoassay
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Official Method Name
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Carcinogenic PAHs RaPID Assay A00201 (SDI 1998) http://www.sdix.com/ |
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Current Revision
| 1998 |
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Media
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WATER |
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Instrumentation
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Immunoassay |
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Method Subcategory
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Organic |
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Method Source
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Citation
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Brief Method Summary
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Inhibition immunoassay, with a colorimetric indicator for competitive binding of analyte and an enzyme-labeled conjugate to surface-immobilized antibodies. Colorimetric response is inversely related to the concentration of analyte in the sample or standard. Calibrated for benzo(a)pyrene. Sensitivity to benzo(a)pyrene less than to benz(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, indeno(1,2,3-cd)pyrene, and chrysene. Reagents are purchased in kits with manufacturers' instructions for sample preparation and analysis. Requirements: a clean water supply to prepare dilutions of water samples; filtration equipment to remove particulates from water samples; an SDI magnetic bead separator, required for the SDI RaPID assay kit; a spectrometer which accepts sample tubes (SDI RaPID Assay) for analyses at visible wavelengths (450 nm primary; 600 or 650 nm reference); equipment to automate sample preparation for large numbers of samples (prefiltration, measurement of uL volumes, rinsing, agitation), so that contact times with reagents are controlled as required; computerized data acquisition and processing. Expendable supplies - approximately $15 per determination. |
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Scope and Application
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Ambient and compliance monitoring. Can be adapted for analysis of soils by Method 4035. Soil screening for polynuclear aromatic hydrocarbons by immunoassay (EPA 1995). |
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Applicable Concentration Range
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0.04 - 5 ug/L as benzo(a)pyrene |
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Interferences
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Carcinogenic PAH tests (sensitivity to possible interferences, compared to benzo(a)pyrene): Sensitivity > benzo(a)pyrene: benzo(a)anthracene, benzo(k)fluoranthene, benzo(b)fluoranthene, indeno(1,2,3-cd)pyrene, chrysene. Sensitivity < benzo(a)pyrene: dibenzo(a,h)anthracene, benzo(ghi)perylene, anthracene. Sensitivity << benzo(a)pyrene: phenanthrene, fluoranthene, pyrene, fluorene, naphthalene, acenaphthalene, acenaphthylene |
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Quality Control Requirements
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A 2 ug/L control solution of benzo(a)pyrene is provided for analysis with every set of samples. Recommended for a kit allowing 100 quantitative determinations: a. calibration with 3 standards and 1 blank, all analyzed in duplicate b. precision: all 46 samples analyzed in duplicate (repeats) c. accuracy: 3 matrix samples, spiked with the target analyte at different levels in the range for quantitative analysis. d. validation: analysis of 4 positive and 4 negative samples by an independent method, for confirmation |
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Sample Handling
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Samples are typically collected in glass containers with Teflon-lined caps. Immediate dilution of water samples with stabilizer (methanol:sample, 1:3, v/v) is recommended to inhibit adsorption of PAHs to the container. Drinking water samples are typically dechlorinated with 0.008% sodium thiosulfate, but the choice of reagents needs to be validated for the kit being used. Samples are held in a refrigerator at 4 oC. Immunoassay reagents and kits are stored in the dark at 4 to 8 oC until use. Water samples generally need to be centrifuged or prefiltered to 0.2 um. Quantitative analysis requires dilution of highly concentrated samples, until they are bracketed by standards in the linear response range. Aliquots of samples and reagents are accurately measured (uL) and mixed for required times, following manufacturer's instructions for use of the materials purchased. |
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Maximum Holding Time
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5 days at 4oC until extraction and analysis |
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Relative Cost
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Less than $50 |
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Sample Preparation Methods
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