This method is for determining trace levels of individual oxygenated hydrocarbons, with boiling points up to 138&176;C, in C 4 liquefied petroleum gas (LPG), light isomerate and naphtha. Mono-oxygenated hydrocarbons determined include C1 through C5 alcohols, and C2 through C6 and 1,4-dioxane. The range of quantitation for 2-butanone is 0.2 to 250 mass-ppm (mg/kg). The range of quantitation for other components may be estimated by multiplying the relative response factor of the component form table 2 times the above values. Inorganic compounds containing oxygen, such as water, are not determined. Carbon monoxide and carbon dioxide are not determined. Unsaturated oxygenated hydrocarbons may be detected but are not identified. Oxygenated hydrocarbons containing other heteroatoms such as nitrogen, chlorine or sulfur are not determined. Certain oxygenated other heteroatoms such as nitrogen, chlorine or sulfur are not determined. Certain oxygenated hydrocarbons are not separated and are reported as composites. See Table 2 for a list of all identified compounds and composites. Some sulfur and nitrogen compounds are known to elute in the oxygenate region of the chromatogram; Figures 2A and 2B show elution times of some identified sulfur and nitrogen compounds.