Solid-phase microextraction polydimethyl siloxane

An attractive approach to isolating analytes is a solid-phase microextraction (SPME). In one approach, which is illustrated in Figure 12.19, a fused silica fiber is placed inside a syringe needle. The fiber, which is coated with a thin organic film, such as polydimethyl siloxane, is lowered into the sample by depressing a plunger and is exposed to the sample for a predetermined time. The fiber is then withdrawn into the needle and transferred to the gas chromatograph for analysis. 

Samples were placed in 20-mL vials and allowed to equilibrate at 25°C. A solid-phase microextraction (SPME) fiber, polydimethyl siloxane/divinyl-benzene, (PDMS/DVB) 65 pm (Supelco Park, Bellefonte, PA), was used for sampling volatile compounds, using the methodology already described [18]. 

Figure 2 T5 pical total ion chromatograms of the static headspace volatiles of ground roasted Ethiopia coffee beans (roast degree L23) obtained by three different solid-phase microextraction fibers. PDMS, polydimethyl siloxane DVB, divinylben-zene CAR, carboxen.

Table 4 Effect of Solid-Phase Microextraction Sampling Time on the Changes of Measured Gas Phase Concentrations Using a lO-gm Polydimethyl Siloxane Fiber...

Figure 2 PDMS SPME fiber equilibrium times for rf-limonene in water (12ppm) and 11.8 °Brix, 10% suspended pulp orange juice (200 ppm). Sample (125 mL) in 250 mL capped (Teflon septa) bottle held overnight at 26°C. PDMS, polydimethyl siloxane SPME, solid-phase microextraction., water , juice.

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