Evaluation of Adsorption Tubes for Air Sampling of C2[sbnd]C4Unsaturated Hydrocarbons

Three different types of adsorption tubes have been tested for suitability in sampling C2[sbnd]C4 unsaturated hydrocarbons. Tubes packed with both a section of Molecular sieve 5A and Tenax GC showed the best retention towards these compounds, and were evaluated with the aid of humidified test atmospheres. Glass tubes packed with anhydrous potassium carbonate and a permeation drier were used in order to reduce the relative humidity of the sample prior to collection onto the adsorption tube. Breakthrough volumes and recoveries were studied in relation to relative humidity and sampling rate. The method has been applied to real air samples. The results indicate that the Molecular sieve 5A/Tenax GC adsorption tube can be successfully used for sampling of C2[sbnd]C4 unsaturated hydrocarbons provided that a drying device is used to reduce the humidity of the sample.