Novel family of multi-layer cartridges filled with a new carbon adsorbent for the quantitative determination of volatile organic compounds in the atmosphere

The ability of a new graphitized carbon black adsorbent (Carbograph 5) to retain volatile organic compounds (VOCs) in air has been investigated through laboratory experiments performed by frontal chromatography. An artificial mixture containing 19 different compounds from C-1 to C-7 at levels of 50 ppb (v/v) each was used as eluent. The amounts of VOCs retained by Carbograph 5 were determined by high-resolution GC-flame ionization detection after thermal desorption at 250 degrees C. The retention features of this adsorbent were compared with those provided by Carbograph 1 and Carbograph 2, two graphitic carbons equivalent in specific surface area and adsorption properties to Carbopack B and Carbopack C, respectively. It was found that Carbograph 5 exhibits safe sampling volumes of VOCs much higher than those of Carbograph 1 and is the only hydrophobic material providing performances comparable to those of some molecular sieve adsorbents. Results obtained indicate that Carbograph 5 can be used alone or in combination with other materials. When combined with lighter adsorbents, it allows the quantitative collection of polar and non-polar VOCs with carbon number higher than 3 in air volumes larger than 51 at any relative humidity. In combination with stronger carbon molecular sieve adsorbents, it makes possible the quantitative collection of components with volatilities ranging from C-2 to C-7 in small samples. (C) 1999 Elsevier Science B.V. All rights reserved.