Abstract
Distortion of the chromatographic profile obtained for hydrocarbons that have been sampled by adsorption onto activated charcoal is a well-known phenomenon. The work reported here helps to better define the causes of chromatographic profile distortion and offers a potential method to avoid chromatographic distortion in some cases through a subsampling technique. The recovery of hydrocarbons from an equimolar mixture was investigated to determine the influence of hydrocarbon concentration on the molar ratios of recovered components. In a one-quart container, hydrocarbon volumes as small as 24 μL (liquid) were sufficient to saturate the surface area available for adsorption on a 99.0 mm2 square of activated charcoal, resulting in significant distortions in the molar ratio and the chromatographic profile of the recovered hydrocarbons. Passive headspace sampling of a similarly small volume of unweathered gasoline spiked onto carpet padding resulted in a significant distortion of the chromatographic profile. The chromatographic profile of the recovered hydrocarbons closely resembled 75% weathered gasoline. Heating the container spiked with unweathered gasoline to evenly distribute the components and then removing a subsample of the carpet padding to a second container for passive headspace analysis greatly reduced the amount of distortion in the resulting chromatogram.
