“…The characterization and measurement of extremely minute amounts (ppb) of these hazardous compounds in ambient air have been seriously hampered by the lack of a reliable sampling system and sensitive instrumentation for direct analysis. Special systems have been developed for concentrating trace organic vapors from large volumes of atmosphere and transferring the collected vapors to an analytical system (8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25), Many collection devices and sorbents have been employed by investigators in air pollution. In general, the concentrating techniques have utilized cryogenic (19)(20)(21)(22)(23)(24).…”