1.1 ,This procedure covers the determination of thiodiglycol (TDG) in soil using pressurized fluid extraction (PFE). A commercially available PFE system2 was used, followed by analysis using liquid chromatography (LC), and detected with tandem mass spectrometry (MS/MS). TDG is qualitatively and quantitatively determined by this method. This method adheres to single reaction monitoring (SRM) mass spectrometry.