Extraction of amino acids from soils and sediments with superheated water

A method of extraction for amino acids from soils and sediments involving superheated water has been investigated. About 75–97 per cent of the amino acids contained in four soils of a soil profile from Illinois were extracted by this method. Deep penetration of water into soil aggregates and partial hydrolysis of peptide bonds during this extraction by water at high temperature are likely mechanisms responsible for the release of amino acids from samples. This extraction method does not require subsequent desalting treatments when analyses are carried out with an ion-exchange amino acid analyzer.