Metrology: Cryogenic sampler for analyzing VOC [Métrologie: Echantillonneur cryogénique pour l'analyse des COV]
Résumé
Cryogenic trapping is an efficient technique to sample VOC and very volatile inorganic compounds such as hydrides in ultra traces. The cryogenic trap is an alternative to sampling systems on solid supports. The cryogenic sampler for hydrides attached to a powerful detector coupling, a GC to MS with induced plasma, ICP/MS. A sampling method based on cryogenics was chosen to conserve intact, up to analysis, all VOC species and notably those with very low boiling point the problems with capturing VOC on absorbents is the selectivity of absorbents, making quantification difficult. In cryogenic capture, VOC are condensed by the vaporization of liquid N2 in a cryostat permitting attainment of - 180° to - 20°C, with sampling tubes covered with glass wool. Collected samples are analyzed by flash thermal desorption developed by Gerstel, connected to GC with flame ionization detector. VOC studied: methanol, acetone, ethyl acetate, p-xylene, dichloromethane, methylethyl ketone, dichloroethane, methylisobutyl ketone, and toluene.