Simultaneous picogram determination of “earthy-musty” odorous compounds in water using solid-phase microextraction and gas chromatography-mass spectrometry coupled with initial cool programmable temperature vaporizer inlet

“Earthy-musty” off-flavor problem in water samples are due to organic compounds present at the sub-part-per-trillion level. Most of the developments in the analysis of tastes and odorous compounds focus on the extraction pre-concentration technique, with detection at picogram per liter level of the earthy-musty off-flavor compounds difficult to be achieved. In this study, a simple, efficient and sensitive method for the analysis of odorous compounds has been developed by the application of solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) with initial cool programmable temperature vaporizer (PTV) inlet for the first time. Compared with initial hot PTV inlet, the initial cool inlet could greatly improve the system sensitivity, especially for the compounds with good volatility, e.g. 2-methylisoborneol (MIB). StableFlex divinylbenzene/Carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber was found to possess the best extraction efficiency towards these odorous compounds in water. Various SPME and PTV conditions have been studied and optimized in detail. The optimized method has been validated with good linearity, precision and accuracy. The method detection limits (MDL) of the targeted odorous compounds were found to be 0.32 ng/L for 2,4,6-trichloroanisole (2,4,6-TCA), 0.14 ng/L for 2,3,6-trichloroanisole (2,3,6-TCA), 0.16 ng/L for 2,3,4-trichloroanisole (2,3,4-TCA), 0.38 ng/L for 2,4,6-tribromoanisole (2,4,6-TBA), 0.16 ng/L for gesomin and 0.15 ng/L for MIB. To the best of our knowledge, this represents the best sensitivity achieved for analysis of gesomin and MIB in water via the simple and efficient SPME method. The current method has been successfully applied in the analyses of different water samples.