Analysis for trace amounts of geosmin in water and fish

Trace amounts of geosmin (trans-1,10-dimethyl-trans-9-decalol) were concentrated from relatively large volumes of water by vegetable oil extraction. After stirring the two phases for 30 min, the dispersed oil was allowed to separate. The oily layer was removed and centrifuged to break the emulsion and separate the two layers. The direct gas chromatographic technique was used to resolve the geosmin from other volatile components on a capillary gas chromatographic column. Volatiles were separated from the oil by securing an aliquot of the oil layer on volatile-free glass wool in the glass liner of the special gas chromatography inlet system. Geosmin was detected at the parts ber billion level with this simple and rapid technique. A technique also was developed for detecting geosmin in fish tissue; it involves steaming the fish to break up the tissue, centrifuging the residual oil phase, and detecting geosmin by capillary gas chromatography. The geosmin remains in the residual oil. Presented in part at the AOCS Annual Meeting in Philadelphia, PA, May 5–9, 1985.