BayCEER: Publications: Soil organic matter extraction using water at ...

Schwesig, D; Göttlein, A; Haumaier, L; Blasek, R; Ilgen, G: Soil organic matter extraction using water at high temperature and elevated pressure (ASE) as compared to conventional methods, Journal of Environmental Analytical Chemistry, 73/4, 253-268 (1999)

Abstract:
Large amounts of soil organic matter can be extracted when using salt solutions or organic solvents, but these extracts do not represent the organic matter soluble under natural conditions. The objective of our study was to evaluate the usefulness of water at high-temperature and elevated pressure for soil organic matter extraction. Soil samples were extracted with water at different temperatures under high pressure (10 MPa), using an Accelerated Solvent Extractor (ASE). These extracts were compared to extracts obtained by conventional methods using distilled water, NaOH and Na4P2O7 solutions. Yields of ASE extracts were up to twenty-fold higher than those of conventional water extracts. UV spectra as well as 1H and 13C NMR spectra revealed high similarity between conventional water extracts and ASE extracts up to 150°C. At higher temperatures, ASE extracts were enriched in aromatic and depleted in O-alkyl-C structures, strongly resembling the NaOH and Na4P2O7 extracts.