ISO 19739:2004 specifies the determination of hydrogen sulfide, carbonyl sulfide, C₁ to C₄ thiols, sulfides and tetrahydrothiophene (THT) using gas chromatography (GC). Depending on the method chosen from those given in its annexes, the application ranges for the determination of sulfur compounds can vary, but whichever of the methods is used, its requirements apply.