A Simple Extraction Procedure for Moderately Volatile Taste and Odor Compounds Such as Geosmin and 2-Methylisoborneol – Method and Applications

Abstract

An extraction procedure is described which is the basis for a convenient method for analysis of large numbers of water samples for 2-methylisoborneol (MIB) and geosmin. The samples are extracted in a 2 1 volumetric flask by stirring with two small volumes of hexane or pentane. An internal standard is added to the dried extracts which are concentrated and analyzed by capillary gas chromatography using a flame ionization detector. Hexane gives better recoveries than pentane, and moderate to high stirring speeds are required. At 250 ng 1−1, hexane extraction is 49%±8% efficient for MIB and 59%±7% for geosmin at moderate stirring speeds. The detection limit is about 20 ng 1−1. This method has been used to analyze for MIB and geosmin in several Canadian water supplies and has been in use since 1984 at the Buffalo Pound Water Treatment Plant to monitor geosmin for various studies: a preliminary survey prior to startup of granular activated carbon (GAC) filtration for taste and odor control, monitoring performance of the GAC filters, and measuring release of geosmin from algae during pre-chlorination.