The term headspace analysis is understood to refer to the analysis of a gas that is in contact with a liquid or solid sample. The results of that gas analysis allow conclusions to be drawn concerning the original composition of the sample. A distinction can be made in that regard between the static headspace technique and the dynamic headspace technique.
The Dynamic Headspace Technique allows volatile and semi-volatile analytes from the gaseous phase above a liquid or solid sample to be enriched on an adsorbent. When using the static headspace technique, the sample is located in a sealed vessel, together with a gaseous phase.
The Dynamic Headspace Technique allows volatile and semi-volatile analytes from the gaseous phase above a liquid or solid sample to be enriched on an adsorbent. A permanent gas stream continually purges the gaseous analytes from the headspace above the sample and transfers them onto an adsorbent. This causes a continual shift in the balance between the headspace and the sample, as a result of which additional analytes are able to outgas. Compared to the conventional headspace technique, this particular technique makes it possible to achieve continuous extraction, thereby leading to a considerably larger quantity of analytes on the adsorbent.
The Dynamic Headspace Technique can be automated using the GERSTEL MultiPurposeSampler (MPS). The incubation and extraction of the adsorbent, together with a drying stage, if any, are performed in a Dynamic Headspace Station (DHS) that forms part of the MPS. Adsorption occurs in sorbent tubes that can be filled with different adsorbents. Once extraction has taken place, these are desorbed in a GERSTEL thermal desorption system and subsequently analyzed using gas chromatography (GC).
When using the static headspace technique, the sample is located in a sealed vessel, together with a gaseous phase. That vessel is kept at a constant temperature by means of a thermostat, until an equilibrium between the two phases has been reached. Once a balanced state has been achieved, an aliquot portion of the gaseous phase is removed from the vessel and analyzed using gas chromatography (GC).
The GERSTEL MultiPurposeSampler (MPS) is fitted with a heated agitator in order to heat up each sample for the same amount of time and to the same temperature and to accelerate the achievement of a balanced state by agitating the sample at the same time. The transfer line customarily encountered when using freestanding headspace units was not required in this case. In order to create as inert a route for the sample as possible, the gaseous phase is drawn directly into a heated, gas-tight autosampler syringe and is then injected into a gas chromatograph inlet (GC-inlet).
