Pressurized hot water extraction (PHWE) is an extraction technique that uses liquid water as extractant (extraction solvent) at temperatures above the atmospheric boiling point of water (100°C/273 K, 0.1 MPa), but below the critical point of water (374°C/647 K, 22.1 MPa) (Fig.1). The use of PHWE in analytical chemistry started with the work in environmental analysis
by Hawthorne and colleagues in the mid-1990s [1,2], and can also be referred to as subcritical water extraction (SWE), superheated water extraction and pressurized liquid extraction or accelerated solvent extraction with water as a solvent. There are a few relatively recent review articles on analytical PHWE, which the reader is recommended to read [3–7].