Dynamic headspace extraction instrumentation

Another configuration of MAP gas-phase extraction relates to dynamic headspace sampling, often referred to as purge and trap sampling. The container can be fitted with an aperture enclosing a trap, or a sorbent, cooled by some common means. This allows the application of a prolonged, low-power irradiation, or of a multi-pulse irradiation of the sample, thus providing a means to extract all of the volatile analytes from the matrix. The contents of the trap can then be transferred (by elution for a chemical or sorbent trap, or by thermal desorption for a cold trap) to an analytical instrument, such as a... 

Analytical methods involving exhaustive extraction of flavor compounds (i.e., liquid/liquid extraction, dynamic headspace) do not take these matrix effects into account. However, new instrumentation and methodologies are yielding improved information on the mechanisms involved in flavor/matrix interactions and the effects on flavor perception. For example, spectroscopic techniques, such as nuclear magnetic resonance (NMR), can provide information on complex formation as a function of chemical environment and have been used to study both intra- and intermolecular interactions in model systems [28,31]. In addition, NMR techniques, initially developed to study ligand binding for biological and pharmaceutical applications, were applied in 2002 to model food systems to screen flavor mixtures and identify those compounds that will bind to macromolecules such as proteins and tannins [32]. Flavor release in the mouth can be simulated with analytical tools such as the retronasal aroma simulator (RAS) developed by Roberts and Acree [33]. These release cells can provide... 

The analysis of volatiles is generally accomplished by an extraction step, followed by concentration, chromatographic separation, and subsequent detection. Well-established methods of analysis include solvent extraction, static and dynamic headspace sampling, steam distillation with continuous solvent extraction, and supercritical fluid extraction. An overview of sample preparation methods is provided by Teranishi (2). The chromatographic profile will vary depending upon the method of sample preparation employed, and it is not uncommon to produce artifacts during this step (3,4). Thermally labile compounds may decompose in the heated zones of instruments to produce a chromatographic profile that is not truly representative of the sample. 

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