Rapid Determination of Geosmin and 2-MIB in Water by Headspace Solid Phase Microextraction Gas Chromatography-Mass Spectrometry

A simple and sensitive technique, headspace solid-phase microextraction (HS-SPME) linked to gas chromatography-mass spectrometry (GC-MS), was developed for the determination of musty odor compounds, geosmin and 2-methylisoborneol. To obtain the highest sensitivity, several parameters of the extraction and desorption procedure were studied and optimized (such as extraction temperature, extraction time, ionic strength, sample volume, desorption temperature and desorption time). The optimum extraction conditions were as follows: extraction temperature 60°C, extraction time 50 min, ionic strength of 0.3 g mL^-1 NaCl, sample volume 20 mL, desorption temperature 250°C, desorption time 5 min. The method showed a good linearity from 2 to 1000 ng L^-1 with the coefficients of determination 0.999 for geosmin and 0.988 for 2-MIB. It provided detection limits of 0.67 ng L^-1 of geosmin and 0.45 ng L^-1 of 2-MIB. The relative standard deviations (R. S. D. S) were within 6.8% for geosmin and 4.4% for 2-MIB. Good recoveries were obtained for tap water (2-MIB 103%, GSM 98%) and lake water (2-MIB 94%, GSM 89%) spiked at 10 ng/L. The method is easily operational and suitable for the determination of musty odor compounds in water. Finally, the method was successfully applied to analyze musty odor compounds in tap water and lake water.