Chromatographic Characterization of Adsorbents for Selective Sampling of Organic Air Pollutants

Seven adsorption materials of various kinds were investigated by inverse gas chromatography. For 25 different organic compounds, specific retention volume (V_q) and adsorption enthalpy (ΔH) with these adsorbents were calculated. According to the measured adsorbent retention ability, the materials can be characterized as follows: Amberlite XAD-4 (styrene-divinyl-benzene-copolymer) and Porapak R (N-vinyl pyrrolidine-polymer) were found to be useful for sampling polar and nonpolar low-volatility compounds, whereas Amberlite XAD-8 (methacrylic acid-polymer) retained only polar high-melting substances. Quantitative sampling of high-melting nonpolar pollutants was possible with Tenax GC (2,6-diphenyl-p-phenylenoxide-polymer). The retention ability of these polymers for volatile compounds such as methylene chloride was very small, hence quantitative collection was impossible. Polar highly volatile compounds can be adsorbed on silica gel, with preference to a modified version for amines. Activated charcoal was the only investigated adsorbent suitable for the efficient sampling of nonpolar highly volatile pollutants.