Author
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Bartelt, Robert |
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Submitted to: Annual Meeting and Expo of the American Oil Chemists' Society
Publication Type: Abstract Only Publication Acceptance Date: 4/28/1996 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: Solid-phase microextraction (SPME) is a powerful, rapid, simple, and rather new technique for headspace sampling of organic compounds. The analyte is adsorbed from the headspace onto a very thin, coated, silica fiber; the fiber is then withdrawn into a modified syringe needle that is used to pierce the injector septum of a GC or GC-MS instrument; the fiber is again exposed in the hot injector, desorbing the sample for analysis. We have used SPME primarily to study the headspace volatiles over fungal and yeast cultures that are attractive to insects (in particular, beetles of the family Nitidulidae). Compounds with a wide span of volatilities and polarities were successfully detected. These ranged from small, polar compounds such as ethanol and acetaldehyde to larger, nonpolar sesquiterpene hydrocarbons. Qualitative analysis of SPME samples by GC-MS is simplified by the absence of a solvent peak and by the very low background "noise." However, quantitation of headspace volatiles by SPME is somewhat complicated because the affinity of fibers for compounds varies greatly with molecular weight and polarity. Headspace/fiber partition coefficients were determined for a variety of microbial compounds; generally SPME is much more sensitive for volatiles with higher molecular weights than for smaller compounds. The partition coefficients also depend on sampling temperature and the fiber coating. Practical parameters involved in quantification of headspace components by SPME will be discussed. |
