Improved gas chromatography procedure for speciated hydrocarbon measurements of vehicle emissions

Abstract A dual-column gas chromatography (GC) procedure was developed for speciated analysis of hydrocarbons in automobile exhaust emissions. Light hydrocarbons (C 1 C 3 ) are analyzed using a 30 m × 0.53 mm GS-Q column; heavier hydrocarbons (C 3 C 12 ) are analyzed using a 60 m × 0.32 mm DB-1 column. The two columns are operated simultaneously within a single GC oven. Variable temperature adsorption traps (VTATs) are used to concentrate samples prior to GC analysis. The detection limits for individual hydrocarbon species are approximately 5–10 ppb (v/v) C. The GC procedure was used to analyze exhaust emissions from both gasoline- and methanol-fueled vehicles. Sample instability was shown to be a problem for diene species in exhaust mixtures —including 1,3-butadiene.