ISO/DIS 9377-4 describes a gas chromatography/flame ionization detection (GC/FID) method to analyze total petroleum hydrocarbons (TPHs) in drinking, surface, waste, and treated waste water. Previous methods used Freon® extraction, which was harmful to the environment. This method uses less harmful solvents such as pentane, hexane, or cyclohexane for sample extraction.

Restek offers mixtures for ISO/DIS 9377-4 analyses. Florisil® cleanup to remove polar compounds is accomplished using a 150-250µm (60/100 mesh) sample preparation column. The analytical column suggested is either an Rtx®-1 or an Rtx®-5 column with dimensions of 10-25m, 0.25-0.53mm ID, and 0.25-1.0µm film thickness.