ASTM: D5412: PAHs and Petroleum Oils in Water
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Official Method Name
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Standard Test Method for Quantification of Complex Polycyclic Aromatic Hydrocarbon Mixtures or Petroleum Oils in Water |
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Current Revision
| Reapproved 2000. Current edition approved May 15, 1993. Published August 1993. |
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Media
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WATER |
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Instrumentation
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Fluorescence Spectroscopy |
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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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This test method consists of fluorescence analysis of dilute solutions of PAHs or petroleum oils in appropriate solvents (spectroquality solvents such as cyclohexane or other appropriate solvents, for example, ethanol, depending on polarity considerations of the sample). The test method requires an initial qualitative characterization step involving both fluorescence emission and synchronous spectroscopy in order to select appropriate calibration standards with similar fluorescence spectra as compared to the samples (see Annex A1 for the definition of spectral similarity). Intensities of peak maxima of suitable emission spectra are then used to develop calibration curves for quantification. NOTE 1 - Although some sections of the characterization part of this test method are similar to Test Method D 3650, there are also significant differences (See Annex A1). Since the purpose and intent of the two test methods are different, one should not be substituted for the other. |
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Scope and Application
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This test method covers a means for quantifying or characterizing total polycyclic aromatic hydrocarbons (PAHs) by fluorescence spectroscopy (Fl) for waterborne samples. The characterization step is for the purpose of finding an appropriate calibration standard with similiar emission and synchronous fluorescence spectra. This test method is applicable to PAHs resulting from petroleum oils, fuel oils, creosotes, or industrial organic mixtures. Samples can be weathered or unweathered, but either the same material or appropriately characterized site-specific PAH or petroleum oil calibration standards with similar fluorescence spectra should be chosen. The degree of spectral similarity needed will depend on the desired level of quantification and on the required data quality objectives. |
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Applicable Concentration Range
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10 or less mg/L |
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Interferences
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The fluorescence spectra may be distorted or quantification may be affected if the sample is contaminated with an appreciable amount of other fluorescent chemicals that are excited and which fluoresce in the same spectral regions with relatively high fluorescence yields. Usually the fluorescence spectra would be distorted at levels greater than 1 to 2 % of such impurities before the quantification would be seriously affected. If the PAH mixture to be analyzed is a complex mixture such as an oil or creosote, it is assumed that a well-characterized sample of the same or similar material is available as a calibration standard so the fluorescent fraction of the mixture can be ratioed against the total mixture. Otherwise, since the samples and standards are weighed, the nonfluorescent portion of the mixture would bias the quantification although the characterization portion of the test method for PAHs given in Annex A1 would be unaffected. |
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Quality Control Requirements
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Calibrate the fluorescence spectrometer frequently to check the wavelength accuracy with an appropriate mercury or other line source and check relative peak ratios for appropriate PAHs (as a check on any spectral correction factor). Check its sensitivity periodically (weekly) using appropriate PAH standards (plastic standards, commercially available, or PAH mixtures in cyclohexane). Naphthalene and anthracene are recommended as instrumental standards. Pyrene, chrysene, or ovalene emit at longer wavelengths and are appropriate for heavier PAH mixtures that also have emission maxima at longer wavelengths. Measure solvent blanks with each sample measurement to check the purity of the solvent and the cleanliness of the fluorescence cells. For each set of samples, measure one sample in triplicate using separate aliquots of the same sample extract. For each set of samples, carry one sample through the entire sample extraction, preparation and analysis procedure in triplicate. |
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Sample Handling
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Collect a representative sample (see Practice D 4489 for water samples). Preserve samples in containers as specified in Practice D 3325. Do not cool samples below 5oC to avoid dewaxing of oil or creosote samples. |
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Maximum Holding Time
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Relative Cost
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$51 to $200 |
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Sample Preparation Methods
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