DETERMINATION OF GEOSMIN AND 2- METHYLISOBORNEOL IN WATER USING SOLID PHASE MICRO EXTRACTION (SPME) AND GAS CHROMATOGRAPHY MASS SPECTROMETRY (GC/MS)Sathya Ganegoda, S.D.M. Chinthaka and Pathmalal M. Manage
A method for the determination of Geosmin and 2- Methylisoborneol (2- MIB) in water by head space solidphase micro extraction (SPME) is presented. Polar, Medium Polar and Non-Polar SPME fiber types have been studied for the optimization of Geosmin and 2- MIB extraction from water. Medium polar SPME fiber (DVB/CAR/PDMS) found to be the most efficient SPME fiber type as both compounds are semi volatile odorous compounds. Extraction conditions such as extraction time, sample volume and temperature were also optimized. The best sample size found to be 10 mL, the optimum extraction time is 15 min. and the best extraction temperature is 40 Â°C. A 3.0 g of Sodium Chloride (NaCl) found to be the best salting out agent. Fiber desorption was carried out at 270 Â°C for 5 minutes at the GC injection port. Injection port was operated in pulsed splitless mode and Helium was used as the carrier gas at a flow rate of 1.1 mL/min. The selected ions for the quantification of Geosmin and 2- MIB are m/z 112, 125 and m/z 95 accordingly. The results showed good linearity over the concentration ranges of both compounds (R2 values Geosmin - 0.9972, 2- MIB - 0.9980) with a recovery of 91.0% for Geosmin and 92.4% for 2- MIB. Minimum Quantification levels for Geosmin is 3.5 ng/L and that level for 2- MIB is 3.0 ng/L. Minimum Detection level for Geosmin is 1.5 ng/L and that level for 2-MIB is 1.3 ng/L. Both values were below the minimum threshold level for humans where human olfactory system detects the Geosmin and 2- MIB at ~ 5 ng/L.