"Cold" solid-phase microextraction method for the determination of volatile halocarbons present in the atmosphere at ultra-trace levels.

Anthropogenic volatile halocarbons are compounds of great enviromnental concern because of their involvement in global change phenomena. They are present in the atmosphere at concentration levels in the order of parts per trillion by volume. The chosen analytical method for their determination is capillary gas chromatography coupled to mass spectrometry, preceded by an enrichment step on suitable adsorbent resins. The method here presented makes use of the solid-phase microextraction as a pre-analytical technique, using sub-ambient temperature in order to enhance the retention capability of the fiber coating. The proposed method was evaluated in terms of extraction efficiency, linearity, reproducibility, andlimits of detection. Results obtained showed that trace atmospheric halocarbons are detectable even when enriching very small air sample volumes. A good chromatographic resolution is obtained as a consequence of the extremely low injection volume. Finally a standard GC-MS instrumentation equipped with a simple split-splitless injector was employed, thus avoiding the use of expensive dedicated apparatus. The method was also applied to the analysis of actual samples collected both in remote, and in semi-remote sites.