ABSTRACT
Standard Methods for the Examination of Water and Wastewater. All these methods follow more or less the same procedures. e detection limits, however, may di er for regulatory purposes. As to cite an example, while the method detection limit (MDL) for an acid extractable compound, pentachlorophenol by the EPA Method 525 for potable water is 1.0 μg/L, its MDL in Method 625 for waste water is whereas the estimated quantitation limit (which is not the same as the MDL) for this compound in the Method 8270 for ground water is 50 μg/L. Such variation may be attributed along with other factors to the extraction procedure and the magnitude of the sample concentration. All these methods are based on extracting the organic analytes by an appropriate technique, followed by concentration, cleanup of the sample extracts for the removal of the interfering substances, and then separation of the compounds in the sample extract on a capillary GC column and subsequently identifying and quantifying the compounds by mass spectrometry. In addition, all these analytical methods to identify and quantify the semivolatile organic compounds in the environmental matrices inherently are based on GC/MS analysis, although their extraction methods may di er. Cleanup steps for the sample extracts may be avoided for clean samples or if no interfering substances are expected to be present. ese methods are brie y highlighted below. Methods 8270 and 526 (U.S. EPA Solid Wastes; U.S. EPA Analytical Method 526), however, are described in detail than the other procedures.
