Author(s): LLOYD S W, LEA J M, ZIMBA P V, GRIMM C C
Geosmin (GSM) and 2-methylisoborneol (MIB) are algae metabolites with muddy/musty odors which contaminate water supplies and can be absorbed by aquatic organisms. Humans can perceive them in water and aquatic food products at ng/l (parts per trillion) concentrations. A rapid method employing solid phase micro extraction (SPME) has been developed for the analysis of GSM and MIB in water. Routine quantification at μg/l concentrations can be accomplished using gas chromatography and flame ionization detection (FID) on a 6 ml aqueous sample with a total analysis time of less than 15 min. Concentration levels of MIB and GSM at 10 ng/l (parts per trillion) can be detected under optimal conditions employing GC/MS in selected ion monitoring mode. Standard solutions and water samples from MIB producing algae cultures were used to compare SPME against purge and trap (P&T) using both flame ionization and mass spectrometric detection. Results obtained from SPME and P&T were similar in terms of reproducibility and sensitivity. This paper reports a simple, rapid method for monitoring the algal production of MIB and GSM at the μg/l range which can be extended to the drinking water levels at the ng/l range of concentrations.