Development of a membraneless extraction module for the extraction of volatile compounds: application in the chromatographic analysis of vicinal diketones in beer.

A membraneless extraction module (MLEM) for the sample preparation of volatile compounds and its use for the chromatographic analysis of vicinal diketones in beer are reported. The extraction process is based on the same principles of gas diffusion (GD) and pervaporation (PV); however it does not use a membrane. This module has a lower chamber where the sample continuously flows, while volatile compounds evaporate to the headspace. Inside the module there is a suspended small reactor, where a small volume of a suitable acceptor solution is placed. This extraction module was tested in the determination of vicinal diketones (VDKs) in beer (CV=5%; LOD=4 microg L(-1)), showing applicability with real samples. Several parameters of the extraction process, such as temperature, sample flow and extraction time, were studied and optimized. This module proved to be a good tool for the sampling of volatile compounds, since the extraction is made without using a membrane avoiding all the robustness problems related with its use.