Evaluation of the reliability of diffusive sampling in environmental monitoring Original Research Article

Diffusive sampling has long been available as an alternative to active sampling in occupational hygiene to determine the concentrations of toxic volatile organic compounds in workplace air. Diffusive sampling has many advantages including increased sampling time, simplicity and lower unit sample cost. On the other hand, its application in environmental monitoring is ambiguous, because the reliability of this technique under environmental conditions is subject to much controversy. The main question is whether the simple uptake model of diffusive sampling can be applied under environmental conditions. In this paper, the applicability of the simplified uptake model of diffusive sampling for benzene, toluene, ethylbenzene and m,p-xylene (BTEX compounds) was studied in the environment. It was found that a critical exposure dose should be exceeded to obtain consistent and reliable analytical data and to ensure that the simplified uptake theory is useful. It was concluded that the main source of uncertainty in environmental applications of diffusive sampling was the use of uptake rates determined in the laboratory. Although the uptake rates seem to be stabilised when the critical exposure limit is exceeded, their determination requires field comparison with a standard reference method.