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 ppmv 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 (ppbv 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.