Chemical characterization of volatile organic compounds (VOCs) through headspace solid phase micro extraction (SPME)

Plants are able to store and emit a wide array of volatile organic compounds, also known as VOCs, which play a pivotal role in their interaction with the ecosystems. These VOCs, released as a mixture of lipophilic compounds with low molecular weight, are produced by different biosynthetic pathways and actively participate in plant defensive strategies against both abiotic and biotic stress factors. Among them, plant-plant interaction, the attraction of pollinators and/or parasitoids and the signaling between symbiont organisms, are the most documented. The development of techniques aimed in trapping, analyze, identify, and quantify plant volatiles, coupled to the evolution of gas chromatography-mass spectrometry analytical methods, as well as the possibility to monitor in-vivo the changes in VOCs production, has significantly increased our knowledge concerning VOCs biosynthesis and their ecological role. This chapter will introduce an overview concerning the ecological role of plant volatiles as well as the biosynthetic pathways involved in their production. Moreover, it will describe the materials as well as the analytical steps that should be followed for static headspace VOCs analysis through solid-phase microextraction (SPME), which is one of the most common, repeatable and accepted technique.