3. Sampling methods

3.1 Samples without concentration

This sampling method consists of introducing the air to be analyzed into a container for transport and storage prior to analysis. The aim is to build up a reserve of gas for processing the sample in the laboratory, under conditions that are easier to control than in the field. If the volume stored is sufficient, it is even possible to repeat the manipulations to assess the reproducibility of the protocol used, or to modify certain parameters (e.g. extraction time, to avoid saturation of the adsorbent or, conversely, to increase detection sensitivity). The main difficulty with this sampling approach is to maintain the integrity of the sample until it is analyzed. This is all the more difficult to achieve when VOC concentrations are low. In all cases,...