Dynamic headspace technique

For this purpose, we developed a modified dynamic headspace technique for the analysis of truffle flesh and the aromatic liquid released during cooking. 

A method for the automated analysis of volatile flavor compounds in foods is described. Volatile compounds are removed from the sample and concentrated via the dynamic headspace technique, with subsequent separation and detection by capillary column gas chromatography. With this method, detection limits of low ppb levels are obtainable with good reproducibility. This method has experienced rapid growth in recent years, and is now in routine use in a number of laboratories. 

The dynamic headspace technique (purge and trap) comprises the continuous extraction of volatile compounds from the matrix into the gas phase followed by a concentration step. The transfer of volatile compounds into the gas phase is limited mainly by their volatility. Although this enables volatile substances to be distinguished from less volatile ones, there is no way of differentiating between substance classes of volatiles during the purge step. 

The search of adequate extraction techniques allowing the identification and quantification of wine volatile compounds has attracted the attention of many scientists. This has resulted in the availability of a wide range of analytical tools for the extraction of these compounds from wine. These methodologies are mainly based on the solubility of the compounds in organic solvents (liquid-liquid extraction LLE, simultaneous distillation liquid extraction SDE), on their volatility (static and dynamic headspace techniques), or based on their sorptive/adsorptive capacity on polymeric phases (solid phase extraction SPE, solid phase microextraction SPME, stir bar sorptive extraction SBSE). In addition, volatile compounds can be extracted by methods based on combinations of some of these properties (headspace solid phase microextraction HS-SPME, solid phase dynamic extraction SPDE). 

This technique is simple, relatively inexpensive, minimizes the formation of artifacts and can accurately quantify volatile substances with low solubility in water, its only disadvantage being its lower sensitivity with respect to dynamic headspace techniques, although this disadvantage is unimportant in most of its applications to forensic toxicology. 

Finally, there are analyses within forensic science, where static headspace gas chromatography can be used as a part of a more complex analysis as fire debris analysis (Ren Bertsch, 1999 Sandercock, 2008), where the static headspace analysis provides complementary information to that provided by dynamic headspace techniques, for the determination of amphetamines and methamphetamines by the addition of potassium carbonate to transform the amine of the stimulant in its unprotonated, volatile form (Seto, 1994), and more recently, the study to substances produced during corpse decomposition (Statheropoulos, et al., 2005 Swann, et al., 2010), where different types of separation techniques are used to characterize the compounds produced in the decomposition and determine how they are produced. 

In the dynamic headspace technique, a carrier gas is passed continuously through the sample under investigation. Constant contact with fresh... 

The static and dynamic headspace techniques are the most common techniques for determination of volatile analytes from aqueous samples. In the latter, also called purge-and-trap, a gas is passed over the sample or through the sample as small bubbles and the volatile compounds in the sample are transported by the gas to a cryogenic or a sorbent trap, before subsequent GC separation. In the more common static headspace technique, the sample vial is thermostated (Figure 2.5) until... 

The SPME method should be regarded as an alternative to the conventional static or dynamic headspace technique, and at the same time serves as a substitute... 

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