Pressurised hot water extraction

In liquid-solid extraction (LSE) the analyte is extracted from the solid by a liquid, which is separated by filtration. Numerous extraction processes, representing various types and levels of energy, have been described steam distillation, simultaneous steam distillation-solvent extraction (SDE), passive hot solvent extraction, forced-flow leaching, (automated) Soxh-let extraction, shake-flask method, mechanically agitated reflux extraction, ultrasound-assisted extraction, y -ray-assisted extraction, microwave-assisted extraction (MAE), microwave-enhanced extraction (Soxwave ), microwave-assisted process (MAP ), gas-phase MAE, enhanced fluidity extraction, hot (subcritical) water extraction, supercritical fluid extraction (SFE), supercritical assisted liquid extraction, pressurised hot water extraction, enhanced solvent extraction (ESE ), solu-tion/precipitation, etc. The most successful systems are described in Sections 3.3.3-3.4.6. Other, less frequently... 

With suitable adjustments to the temperature, also subcritical water extraction (SWE) or pressurised hot water extraction (PHWE) allows selective extraction of polar (chlorinated phenols), low-polarity (PCBs and PAHs) and nonpolar (alkanes) organic compounds from industrial soils [418]. 

Pressurised hot water extraction has been used to isolate polycyclic aromatic hydrocarbons from soil [104,105]. Ramos et al. [106] reported an rapid (ten minutes) miniaturised pressurised liquid extraction method using only 100 pi solvent for extracting polycyclic aromatic hydrocarbons from soil. 

Pressurised hot water extraction has been employed [57-59]. It is rapid and typically needs only 100 p,l of extractant. 

Kuosmanen, K., T. Flyotylainen, K. Flartonen, J.A. Jonsson, and M.-L. Riekkola. 2003. Analysis of PAH compounds in soil with on-line coupled pressurised hot water extraction-microporous membrane liquid-liquid extraction-gas chromatography. Anal. Bioanal. Chem. 375 389-399. 

Andersson, T., T. Pihtsalmi, K. Hartonen, T. Hyotylainem, and M.L. Riekkola. 2003. Effect of extraction vessel geometry and flow homogeneity on recoveries of polycyclic aromatic hydrocarbons in pressurised hot water extraction. Anal. Bioanal. Chem. 376 1081-1088. 

Kousmanen K, Hybtylainen T, Hartonen K, and Riekkola M-L. Analysis of polycyclic aromatic hydrocarbons in soil and sediment with on-line coupled pressurised hot water extraction, hoUow fibre microporous membrane hquid-hquid extraction and gas chromatography. Analyst 2003 128 434- 39. 

Kuosmanen, K., Hyotylainen, T., Hartonen, K., and Riekkola, M. L., Pressurised hot water extraction coupled on line with liquid chromatography-gas chromatography for the determination of brominated flame retardants in Sediment Samples, J. Chromatogr. A, 943, 113-122, 2002. 

Song, T., Pranovich, A. and Holmbom, B. (2008) Extraction of galactoglucomannan from spruce wood with pressurised hot water. Holzforschung, 62, 659-666. 

Also, subcritical (hot/liquid) water can be used as a mobile phase for packed-column RPLC with solute detection by means of FID [942]. In the multidimensional on-line PHWE-LC-GC-FTD/MS scheme, the solid sample is extracted with hot pressurised water (without the need for sample pretreatment), and the analytes are trapped in a solid-phase trap [943]. The trap is eluted with a nitrogen flow, and the analytes are carried on to a LC column for cleanup, and separated on a GC column using the on-column interface. The closed PHWE-LC-GC system is suitable for many kinds of sample matrices and analytes. The main benefit of the system is that the concentration step is highly efficient, so that the sensitivity is about 800 times better than that obtained with traditional methods [944]. Because small sample amounts are required (10 mg), special attention has to be paid to the homogeneity of the sample. The system is... 

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