Analyte uptake into the sampler proceeds by permeation through a polydimethylsiloxane (PDMS) membrane.  The mechanism of this process is similar to that responsible for analyte separation in gas chromatographic columns coated on the inside with PDMS stationary phases. This similarity forms the basis for the estimation of the uptake rates (and hence concentrations) of the pollutants found in the field, without prior knowledge of their presence in the sampled environment. Further, PDMS is a hydrophobic material, which makes it possible to adapt the sampler to high humidity environments. Theoretical considerations and experimental results suggest that the uptake kinetics is nearly insensitive to temperature variations typical for indoor environments.

The design of the sampler further allows for solvent desorption to be performed in the same vial in which sampling took place and for direct introduction of the vial into a GC autosampler. This reduces the number of sample preparation steps (and hence potential errors), thus helping with high throughput analysis.

In the presentation, the theoretical and practical aspects of the technique with regards to uptake kinetics, temperature and humidity effects will be discussed. Method of estimation of the calibration constants using the analyte retention properties in gas chromatography will be introduced. The application of the passive samplers in the area of vapor intrusion studies will be presented with an example from a real field site.