New universal,portable and cryogenic sampler for time weighted average monitoring of H2S,NH3, benzene,toluene, ethylbenzene,xylenes and dimethylethylamine

A new cryogenic integrative air sampler (patent application number 08/00669), able to overcome many of the limitations in current volatile organic compounds and odour sampling methodologies is presented. The sample is spontaneously collected in a universal way at 15 mL/min, selectively dried (reaching up to 95% of moisture removal) and stored under cryogenic conditions. The sampler performance was tested under time weighted average (TWA) conditions, sampling 100 L of air over 5 days for determination of NH₃, H₂S, and benzene, toluene, ethylbenzene and xylenes (BTEX) in the ppm_v range. Recovery was 100% (statistically) for all compounds, with a concentration factor of 5.5. Furthermore, an in-field evaluation was done by monitoring the TWA inmission levels of BTEX and dimethylethylamine (ppb_v range) in an urban area with the developed technology and comparing the results with those monitored with a commercial graphitised charcoal diffusive sampler. The results obtained showed a good statistical agreement between the two techniques.