Using solid phase extraction to study organic matter in hydrothermal systems in the Russian Far East

The paper describes the process of solid phase extraction as a method of natural waters sample preparation, in particular thermal waters, for subsequent instrumental analysis of organic matter of medium volatility. The author outlines main steps of this process, which consist of concentrating the target compounds of interest in the sorbent, purifying them from impurities, and changing the initial matrix to a more suitable medium for chromatographic analysis. The main advantages of this method of sample preparation over traditional liquid-liquid extraction are the effective absorption of a large number of organic compounds and possibility to store them for a long time before analysis without changing their composition and concentration, using small sample volumes and organic solvents. Solid phase extraction is suitable for both in vitro and on-site water sampling applications, in this way making easier field investigations of hard-to-reach hot springs. This sample preparation method needs a laboratory and field setup, as well as a device for conditioning and elution of sorbents, their description also provided in this paper. It also presents the main results of a long-term study of medium volatile organic compounds in thermal and cold waters from geothermal fields in the Far East. The aanalysis was carried out by the solid phase extraction method with the use of silica gel (C18) sorbent cartridges and gas chromatography-mass spectrometry. For the first time, a wide range of organic compounds have been identified for these deposits, including alkanes, aromatic hydrocarbons, carboxylic acids and their esters in hot water. The origin of these components is related to thermocatalytic processes of biogenic organic residue transformation. Biogenic terpenes and steroids are widely spread in cold waters within geothermal field areas.