Method EPA 537
Method EPA 537 ( Perfluorinated Alkyl Acids) is used for the analysis perfluorinated alkyl acids. The analytes that are detected and quantified by this method are perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorohexanesulfonic acid (PFHxS), perfluoroheptanoic acid (PFHpA) and perfluorobutanesulfonic acid (PFBS).
The samples are fortified with surrogates and passed through a solid phase extraction (SPE) cartridge containing polystyrenedivinylbenzene (SDVB) to extract the method analytes and the surrogates. The compounds are eluted from the solid phase with a small amount of methanol and then concentrated to dryness with nitrogen in a heated water bath, and then adjusted to a 1-mL volume with 96:4% (vol/vol) methanol:water after adding the internal standards. The extracts are injected into liquid chromatograph where the analytes are separated based on polarity and passed into two mass spectrometer in tandem for identification based on the molecular masses of the fragmented compounds. In addition, this analysis provides a high precise quantitation of these compounds.