Headspace Sampling: An “Evergreen” Method in Constant Evolution to Characterize Food Flavors through their Volatile Fraction
This chapter is a survey on a sampling technique grown in parallel to gas chromatography since its early years, and which nowadays enjoys a remarkable renewal of interest thanks to the new strategies of analysis introduced with the “omics” sciences and adopted in food (aroma) analysis, and the continuous evolution of technology (mainly multidimensional separation techniques and mass spectrometry) and data elaboration. After the introductory sections concerning headspace definitions and history, the chapter describes the approaches to static headspace (S-HS) and dynamic headspace (D-HS), and to high-concentration capacity sampling techniques. The latter are techniques bridging the two approaches S-HS to D-HS, where the analytes are accumulated from a vapor or liquid phase on a stationary phase by sorption or adsorption. The following sections deal with quantitation with headspace sampling in both static and dynamic modes illustrating the approaches that can be adopted as a function of the physical status (liquid or solid) of the investigated matrix. The last section describes the use of headspace with non-separative methods, i.e., directly combined to mass spectrometry and chemometric elaboration without a preliminary chromatographic separation.