PURGE-AND-TRAP EXTRACTION OF GEOSMIN AND 2-METHYLISOBORNEOL FROM SOIL

Although a number of techniques are available for estimating the bioma ss of filmentons microorganisms in soil, determination of their activi ty is much more difficult. We report on preliminary studies evaluating the potential use of the volatile microbial secondary metabolites geo smin and methylisoborneol as indicators of activity of filamentous mic roorganisms. The purge-and-trap technique for analysis of low concentr ations of volatile organic compounds in air and water was tested for e xtracting the earthy-musty odor compounds geosmin and 2-methylisoborne ol from soil. Two variations of this method were tried, one in which s oil samples were placed in water for purging and another in which samp les were purged with no added water. Volatile organic compounds purged from soil were collected on a porous polymer sorbent, Tenax TA. Natur ally occurring geosmin and 2-methylisoborneol and added standards were successfully extracted from soil by both methods. Recovery efficienci es, however, were low. Results indicated that wet purging was the most efficacious extraction method yielding maximum recovery rates of adde d geosmin and 2-methylisoborneol standards of 15 and 24%, respectively .