1.1 ,This procedure covers the determination of Diisopropyl Methylphosphonate (DIMP), Ethyl Methylphosphonic Acid (EMPA), Isopropyl Methylphosphonic Acid (IMPA), Methylphosphonic Acid (MPA) and Pinacolyl Methylphosphonic Acid (PMPA), referred to collectively as organophosphonates (OPs) in this test method, in soil. This method is based upon solvent extraction of a soil by pressurized fluid extraction (PFE). The extract is filtered and analyzed by liquid chromatography/tandem mass spectrometry (LC/MS/MS). OPs are qualitatively and quantitatively determined by this method.