Fused silica open tubular columns are efficient, mechanically strong, and relatively inert, so compounds with a variety of functional groups can be chromatographed on the same column (1). For these reasons a chemically bonded fused silica column was selected for the separation and quantification of hydrocarbons and oxygenated compounds emitted from vegetation. When analyzing vegetative emissions, however, it was observed that the retention times of individual compounds varied about 0.25 minute, which was about 10 times greater variation than that of similar standards. This variability made identification and quantification of the compounds difficult, particularly with closely eluting peaks. This paper describes the influence of water on the retention times of homologous series of alkanes, alkenes, and aldehydes on a fused silica open tubular column which may provide added understanding of water-related retention time variability.