Chapter 2: Antioxidants Recovery and Extraction Check Access

The names of the steps mediated between sampling and analytical sample are critically considered, and differences between sample pretreatment and sample preparation are clarified in this chapter. In dealing with the extraction of antioxidants from solid samples, conventional extraction and Soxhlet extraction are first considered, and the improvements of the latter to overcome typical shortcomings of the technique by applying auxiliary energies are discussed. Then, microwave-assisted extraction, its modes, performance, and key applications are critically exposed; ultrasound and the bad use of concepts related with this type of energy are clarified before discussing typical and especial applications of ultrasound-assisted extraction in the antioxidants field. The advantages and limitations of superheated liquids and supercritical fluids for antioxidants extraction are critically discussed, before considering liquid samples (or extracts from solid samples) and their treatment by liquid–liquid extraction and by liquid–solid extraction (or solid-phase extraction, SPE). Both techniques are compared for the sake of proper selection. The growth of green-chemistry practice in dealing with antioxidant extraction has been considered of paramount interest, as well as the comparison of methods based on different techniques for selection of the most appropriate in each situation.