Isolation and determination of dissolved organic sulphur compounds — development of the organic group parameter DOS

A procedure has been worked out for the determination of organic sulphur compounds (OSCs) in aqueous solution. They are isolated from water by solid phase extraction on macroporous resins and reversed-phase sorbents. The total sulphur content of the extracts is determined via a process of thermal cracking and hydrogenation (pyrohydrogenolysis) of small amounts of extract in a heated quartz tube (1100°C) flushed with hydrogen. Sulphur is detected at a wavelength of 394 nm in the hydrogen flame of a flame photometer. The flame photometric detector (FPD) is calibrated with a coulometric H₂S-generator. The procedure of solid phase extraction and subsequent pyrohydrogenolysis/flame photometry of the extracts can be used to determine the organic group parameter DOS (Dissolved Organic Sulphur) in the range of 20–1000 μg/1.