Carboxen/polydimethylsiloxane CAR/PDMS

In the early 90s, a new technique called solid-phase-micro extraction (SPME), was developed (Arthur and Pawliszyn, 1990). The key-part component of the SPME device is a fused silica fiber coated with an adsorbent material such as polydimethylsiloxane (PDMS), polyacrylate (PA) and carbowax (CW), or mixed phases such as polydimethylsiloxane-divinylbenzene (PDMS-DVB), carboxen-polydimethylsiloxane (CAR-PDMS) and carboxen-polydimethyl-siloxane-divinylbenzene (CAR-PDMS-DVB). The sampling can be made either in the headspace (Vas et al., 1998) or in the liquid phase (De la Calle et al., 1996) of the samples. The headspace sampling in wine analyses is mainly useful for quantifying trace compounds with a particular affinity to the fiber phase, not easily measurable with other techniques. Exhaustive overviews on materials used for the extraction-concentration of aroma compounds were published by Ferreira et al. (1996), Eberler (2001), Cabredo-Pinillos et al. (2004) and Nongonierma et al. (2006). Analysis of the volatile compounds is usually performed by gas chromatography (GC) coupled with either a flame ionization (FID) or mass spectrometry (MS) detector. 

We are interested in trace volatile sampling and measurement with emphasis on odour measurement. Commercially about 11 SPME fibre types are available such as those from Supelco , but in the case of odour (trace volatile) detection in air, we have found that three fibre types are most applicable. These comprise 100 pm polydimethylsiloxane (PDMS), 65 pm polydimethylsiloxane/divinylbenzene (PDMS/DVB) and 75 pm carboxen/polydimethylsiloxane (CAR/PDMS) types. Our previous work has investigated the use of both 100 pm PDMS and 65 pm PDMS/DVB fibre types, and we have adopted the latter after initial screening studies. 

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