Significance and Use
This test method is useful for characterization and rapid quantification of PAH mixtures including petroleum oils, fuels, creosotes, and industrial organic mixtures, either waterborne or obtained from tanks.
The unknown PAH mixture is first characterized by its fluorescence emission and synchronous scanning spectra. Then a suitable site-specific calibration standard with similar spectral characteristics is selected as described in Annex A1. This calibration standard may also be well-characterized by other independent methods such as gas chromatography (GC), GC-mass spectrometry (GC-MS), or high performance liquid chromatography (HPLC). Some suggested independent analytical methods are included in References (1–7) and Test Method D4657. Other analytical methods can be substituted by an experienced analyst depending on the intended data quality objectives. Peak maxima intensities of appropriate fluorescence emission spectra are then used to set up suitable calibration curves as a function of concentration. Further discussion of fluorescence techniques as applied to the characterization and quantification of PAHs and petroleum oils can be found in References (8–18).
For the purpose of the present test method polynuclear aromatic hydrocarbons are defined to include substituted polycyclic aromatic hydrocarbons with functional groups such as carboxyl acid, hydroxy, carbonyl and amino groups, and heterocycles giving similar fluorescence responses to PAHs of similar molecular weight ranges. If PAHs in the more classic definition, that is, unsubstituted PAHs, are desired, chemical reactions, extractions, or chromatographic procedures may be required to eliminate these other components. Fortunately, for the most commonly expected PAH mixtures, such substituted PAHs and heterocycles are not major components of the mixtures and do not cause serious errors.
Scope
1.1 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.
1.2 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.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
