ABSTRACT
Introduction In odor analysis, gas chromatography (GC) techniques are used as the main analytical method because the majority of odor compounds are volatiles. In order to determine odor compounds in various sample matrices at trace levels, a GC method usually requires sample preparation (e.g., an extraction and enrichment step) before GC analysis. However, no single sample preparation technique is appropriate for every type of analyte or matrix. In the past decades, the development of miniaturized and solventless (or solvent-minimized) sample preparation methods has been recognized as one of the most important projects because it provides many bene€ts such as high sensitivity, small sample volume, fast analysis, high sample throughput, low operational cost, and low solvent consumption. As a typical example of the miniaturized sample preparation methods, solid-phase microextraction (SPME) (Arthur and Pawliszyn 1990) and stir
Introduction ........................................................................................................ 1 Sequential stir bar sorptive extraction ............................................................ 2
Instrumentation ............................................................................................. 3 Sequential stir bar sorptive extraction........................................................ 4 TD-GC-(NPD)/MS ....................................................................................... 4 Extraction ef€ciency of odor compounds .................................................. 6 Analysis of beer ............................................................................................. 9
Sequential SBSE with PDMS stir bar and EG Silicon stir bar .................... 12 Stir bar sorptive extraction with new phase stir bar .............................. 12 Extraction ef€ciency of odor compounds ................................................ 14
Conclusion ........................................................................................................ 18 Acknowledgments ........................................................................................... 19 References .......................................................................................................... 19
bar sorptive extraction (SBSE) (Baltussen et al. 1999) have been developed in the last decades. These methods are simple, solventless techniques allowing the extraction and concentration in a single step. Also, these methods provide enhanced sensitivity because the extracted fraction (on a €ber or on a stir bar) can be introduced quantitatively into a GC system by thermal desorption (TD). Although both SPME and SBSE can be used in immersion mode and in headspace mode, for odor analysis, SPME is mainly used in the headspace mode (HS-SPME), whereas SBSE is most often used in the immersion mode. It is known that the enrichment factor for SBSE, which is determined by the analyte recovery in the extraction phase (polydimethylsiloxane [PDMS]), is higher than that of SPME because of 50-250 times larger volume of extraction phase on the stir bar. SBSE has been successfully applied to analysis of odor compounds in various sample matrices, for example, water, beverages, fruits, herbs, plant material, essential oils, and vinegar (David and Sandra 2007).
