Multiple Headspace-Solid-Phase Microextraction (MHS-SPME): an application to quantification of mushroom volatiles

When SPME is chosen as sample preparation technique, the decision of which approach is the most convenient depends upon sample matrix, its complexity and extraction method (headspace vs. immersion). In the case of solid matrices, the external standard method is the least indicated, since it doesn’t take into account the so called “matrix effect”. This means that the HS-SPME extraction of a single component would produce different results whether extracting the compound alone or embedded in a matrix, where it undergoes several chemical interactions with other constituents. On the other hand, the internal standard method doesn’t assure that the added standard will undergo the same matrix effect of analytes. Similarly, the standard addition method cannot guarantee the same behavior toward the extraction from both the added and the native substance. An interesting alternative to the classical calibration procedure is represented by Multiple Headspace-Solid-Phase Microextraction (MHS-SPME), first introduced by Kolb et al. in 1977 for headspace analysis [1]. It consists of a consecutive series of extractions carried out on the same sample, from where the values of peak areas for an analyte are registered. Through the application of the theoretical principles, it is possible to measure some specific values, such as the b parameter, that allow predicting the amount of the analyte inside the solid matrix. In this study, the MHS-SPME has been applied to the investigation of a complex sample, relevant to the food area, which is the flavor of the cultivated mushroom Agaricus bisporus, also known as “champignon”. Theory of MHS-SPME, analytical method and results will be discussed, with a focus on the possible extended use of this methodology in the flavor and fragrance field.