Polydimethylsiloxane/divinylbenzene

In the 1990s, Pawliszyn [3] developed a rapid, simple, and solvent-free extraction technique termed solid-phase microextraction. In this technique, a fused-silica fiber is coated with a polymer that allows for fast mass transfer—both in the adsorption and desorption of analytes. SPME coupled with GC/MS has been used to detect explosive residues in seawater and sediments from Hawaii [33]. Various fibers coated with carbowax/divinylbenzene, polydimethylsiloxane/divinylbenzene, and polyacrylate are used. The SPME devices are simply immersed into the water samples. The sediment samples are first sonicated with acetonitrile, evaporated, and reconstituted in water, and then sampled by SPME. The device is then inserted into the injection port of the GC/MS system and the analytes thermally desorbed from the fiber. Various... 

Concentrator materials of choice are often polymers. Polydimethylsiloxane (PDMS), or a polydimethylsiloxane/divinylbenzene copolymer (PDMS/DVB) are favored choices for explosive molecules. PDMS are often used in the form of solid-phase microextraction (SPME) fibers. PDMS/DVB is often used in the form of microspheres with diameters in the 50- to 75-pm range. Detailed considerations for use of SPME fibers is given on a website maintained by the University of Western England [19], It references a more complete treatise [20], Other geometries, such as stacked spheres, have also been used successfully [21],... 

Figure 15.4 Binding of bombykol to BmPBP at pH 7 as demonstrated by the cold-binding assay. After removal of the unbound ligand, bound bombykol was extracted from the ligated protein with a solid phase microextraction syringe (SPME, 65 pm polydimethylsiloxane divinylbenzene coating). Under the same conditions, but at low pH (5), the amount of ligand extracted is not significantly different from the amount extracted from a buffer solution (control).

At present, polydimethylsiloxane, polyacrylate, and carbowaxT -divinylbenzene or polydimethylsiloxane-divinylbenzene are most often used as stationary phases. Nonpolar analytes are isolated with the aid of polydimethylsiloxane for separation of polar compounds, polyacrylate is applicable. 

Heterocyclic aromatic amines Food Carbowax, carbowax-divinylbenzene, polydimethylsiloxane-divinylbenzene, polyacrylate HPLC-UV... 

Solid-phase extraction devices and applications are evolving rapidly, and novel techniques that stretch the classical definition of SPE are becoming routine. Pawliszyn introduced solid-phase micro extraction (SPME) in 1989,5,14 and a commercial apparatus is available from Supelco (Bellefonte, PA). The SPME apparatus is merely a modified syringe that houses a fused silica optical fiber coated with an immobilized polymer film. The fiber can be exposed for extraction and then retracted for insertion or removal from the sample vial or instrument. Both manual and autosampler devices are available and each can be adjusted for proper fiber depth. Several coatings are available with varying thickness including polydimethylsiloxane, polyacrylate, polydimethylsiloxane/divinylbenzene, and carbowax/divinylben-zene. In contrast to SPE, which is an exhaustive extraction approach, SPME will extract only a fraction of an available analyte, hence it is not suitable for the isolation of impurities and degradants in most applications.15... 

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. 

The fiber carboxen-polydimethylsiloxane-divinylbenzene (CAR-PDMS-DVB 50/30 xm x 2cm) proved to be optimal in the GC-MS analysis in terms of the maximum signal recorded for each compound and the simpler sampling procedure and operating conditions (ionic strength, sample temperature, adsorption time) (Fedrizzi et al., 2007a). 

Organochlorine fungicides nuarimol, triadimenol, triadimefon, fol-pet, voinclozolin, and penconazole in wine can be extracted by using a polydimethylsiloxane-divinylbenzene (PDMS/DVB) 60-pm fiber with immersion of the fiber into a 3mL sample at room temperature for 30min. Coupled with LC/DAD analysis, LODs ranging between 4 and 27 pg/L and were reported (Millan et al., 2003). 

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. 

Figure 2. Replicate gas chromatograms of volatiles from combustion of paper sampled with a polydimethylsiloxane/divinylbenzene (PDMS/DVD) SPME fibre.

A -nitrosodibutylamina and A -nitrosodibenzylamina. This method is based on the isolation of the compounds by steam distillation, followed by the SPME in the distillate headspace using a polyacrylate coated silica fiber, and the determination by GC-TEA. Recoveries ranged between 41% and 112%. Nitrosamines in environmental matrixes (air, tobacco, and seawater) were preconcentrated on polydimethylsiloxane/divinylbenzene and the recovery of different nitrosamines from different matrixes varied between 95% and 98%. °" ... 

One of the first applications of SPME to phthalate analysis was the development of a method for the extraction of DEP from water. The final analysis was done by LC-UV. Different parameters were optimized including four types of fibers. Carbowax-template resin (CW-TRP) and polydimethylsiloxane-divinylbenzene (PDMS-DVB) were found suitable to perform phthalate extraction. The other two fibers, polyacrylate (PA) and polydimethylsiloxane (PDMS), were discarded due to low response and broad peaks, respectively. Samples were extracted at room temperature by direct exposition of the fiber to the sample, previously enriched with 25% of NaCl. The linearity achieved was good from 5 to 50 /rg/1. Higher concentrations show a lost of linearity that could suggest the saturation of the fiber coating. Detection limit was 1 ng/ml. 

Lu et al. described the trace determination of sulfonamide residues in meat with a combination of SPME and LC-MS. Fiber coated with a 65 p,m thickness of polydimethylsiloxane/divinylbenzene (PDMS/DVB) was used to extract sulfonamides at optimum conditions. Analytes were desorbed with static desorption in an SPME-HPLC desorption chamber for 15 min and then determined by LC-MS. The linear range was 50-2000 p-g/kg, with RSD values below 15% (intra-day) and 19% (inter-day) and detection limits 16-39 pg/kg. Some meat samples collected from the local market contained residues of sulfonamides ranging from 66 to 157 pg/kg. The results demonstrated that the SPME-LC-MS system could effectively analyze residues of sulfonamides in meat products. 

PDMS/DVB, polydimethylsiloxane/divinylbenzene coated fiber SPME, solid-phase microextraction. 

Polydimethylsiloxane-divinylbenzene (PDMS-DVB) Nonpolar to moderate polar... 

LLE, liquid-liquid extraction MAE, microwave-assisted extraction SEE, solid-phase extraction SPME, solid-phase microextraction LPME, liquid-phase microextraction SOME, single-drop microextraction D-LLLME, dynamic liquid-liquid-liquid microextraction SEE, supercritical fluid extraction MIP, molecularly imprinted polymers sorbent SPMD, device for semipermeable membrane extraction PDMS, polydimethylsiloxane coated fiber PA, polyacrylate coated fiber CW-DMS, Carbowax-divinylbenzene fiber PDMS-DVB, polydimethylsiloxane divinylbenzene fiber CAR-PDMS, Carboxen-polydimethylsiloxane coated fiber DVB-CAR-PDMS, divinylbenzene Carboxen-polydimethylsiloxane coated fiber CW-TPR, Carbowax-template resin HS-SPME, headspace solid-phase microextraction MA-HS-SPME, microwave-assisted headspace-solid-phase microextraction HEM, porous hollow fiber membrane PEl-PPP, polydydroxylated polyparaphenylene. 

Polydimethylsiloxane/ divinylbenzene (PDMS/DVB) 65 p.m Suitable for polar volatiles... 

C Sala, M Mestres, MP Marti, O Busto, J Guasch. Headspace solid phase microextraction method for determining 3-alkyl-2-methoxypyrazines in musts by means of polydimethylsiloxane-divinylbenzene fibers. J Chromatogr A... 

A further example for application of SIDA in fragrance analysis is the quantification of skatole in soap. For this analysis, the SPME technique using 65 iim polydimethylsiloxane/divinylbenzene (PDMS/DVB) coated fiber was applied. Headspace sample was prepared as follows 1 g of soap was dispersed in 10 ml of distilled water, spiked with 1 ppm ds-skatole, and placed in a sealed 100-ml vial containing a Teflon magnetic stirring bar. The sample was equilibrated at 60°C for a period of 30 min. The fiber was carefully introduced in the headspace, and perfume oil constituents were extracted for 30 min under magnetic stirring. 

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