Polydimethylsiloxane fiber solid-phase microextraction

Solid-phase microextraction (SPME) consists of dipping a fiber into an aqueous sample to adsorb the analytes followed by thermal desorption into the carrier stream for GC, or, if the analytes are thermally labile, they can be desorbed into the mobile phase for LC. Examples of commercially available fibers include 100-qm PDMS, 65-qm Carbowax-divinylbenzene (CW-DVB), 75-qm Carboxen-polydimethylsiloxane (CX-PDMS), and 85-qm polyacrylate, the last being more suitable for the determination of triazines. The LCDs can be as low as 0.1 qgL Since the quantity of analyte adsorbed on the fiber is based on equilibrium rather than extraction, procedural recovery cannot be assessed on the basis of percentage extraction. The robustness and sensitivity of the technique were demonstrated in an inter-laboratory validation study for several parent triazines and DEA and DIA. A 65-qm CW-DVB fiber was employed for analyte adsorption followed by desorption into the injection port (split/splitless) of a gas chromatograph. The sample was adjusted to neutral pH, and sodium chloride was added to obtain a concentration of 0.3 g During continuous... 

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... 

Nitrobenzene, 2,4-dinitrotoluene and 2,6-dinitrotoluene were determined in water by GC-EC or GC-CLD thermal energy analyzer (TEA) and by EI-MS, CI-MS and NICI-MS455, after solid-phase microextraction (SPME) with polydimethylsiloxane coated fiber. SPME is a technique to concentrate organic compounds dissolved in an aqueous matrix by adsorption on a solid stationary phase immobilized on a fused silica fiber. The analytes were thermally desorbed directly into the GC injector LOD was 9 pg/L for nitrobenzene and 15 pg/L for the dinitrotoluenes456. 

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],... 

Sample preparation for GC/MS analysis of volatile compounds in wines and extracts was usually performed by liquid-liquid extraction with dichloromethane (Cutzach et al., 1997 Perez-Coello et al., 1999 Cadahia et al., 2003). Direct extraction of volatiles from the wood by headspace (HS) solid-phase microextraction (SPME) using a polydimethylsiloxane (PDMS) fiber allowed to analyze compounds,... 

Several SP materials have been used for the extraction of FRs from aqueous samples, plasma and milk (Table 31.7). Similar materials have been used for all FRs. Typical SP materials include Ci8 and Cg bonded to porous silica, highly cross-linked poly(styrene divinylbenzene) (PS-DVB), and graphitized carbon black (GCB). It is also possible to use XAD-2 resin for extraction of various FRs, pesticides, and plastic additives from large volumes of water (100 1). The analytes can then be either eluted from the resin by acetone hexane mixture, or Soxhlet extracted with acetone and hexane. For a specific determination of diphenyl phosphate in water and urine, molecularly imprinted polymers have been used in the solid phase extraction. The imprinted polymer was prepared using 2-vinylpyridine as the functional monomer, ethylene glycol dimethacrylate as the cross linker, and a structural analog of the analyte as the template molecule. Elution was done with methanol triethylamine as solvent. Also solid phase microextraction (SPME) has been applied in the analysis of PBDEs in water samples. The extraction has been done from a headspace of a heated water sample (100°C) using polydimethylsiloxane (PDMS) or polyacryl (PA) as the fiber material. ... 

Before applying solid-phase microextraction to the water extracts obtained from hot water extraction of rosemary, optimization of experiments were conducted to determine the optimum working conditions for SPME, including water volume, SPME time, and carry over effect. Polydimethylsiloxane fiber (PDMS, 100 tun, Supelco, Bellefonte, PA) was used for performing solid-phase microextraction. 

Solid phase microextraction (SPME) involves extraction onto a thin fiber and the technique has become more prevalent recently and additionally provides a preconcentration of analytes prior to analysis. The fibers used in the technique can be coated with a range of stationary phases and a nonpolar phase such as polydimethylsiloxane (PDMS) is typically used for the extraction of derivatized organotin species. An equilibrium is established between the sample extract solution (or the headspace above the solution) and the stationary phase coating the fiber. The analytes are then typically desorbed from the fiber for analysis, for example, using thermal desorption during GC analysis. The technique allows rapid and solvent-free extraction of the analytes. Very good extraction has been achieved for water samples however, the technique has been shown to be more variable with more complex matrices. 

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

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. 

Solid-phase microextraction (SPME) in open-tobular fused-silica capillary columns or in fused-silica or Carbowax-templated poly(divinylbenzene) resin fibers coated or filled with a stationary phase (polydimethylsiloxane or polyacrylate) 2 has recently been used to extract analytes from liquid or gaseous samples. This procedure is more restricted to the extraction of volatile compounds, which are... 

The solid-phase microextraction device (SPME) was purchased from Supelco Co. (Bellefonte, PA). The following types of SPME fiber were used polydimethylsiloxane (PDMS) with lOO-pm thickness, PDMS/ divinylbenzene (DVB) with 65-pm thickness, and Carboxen (Supelco Co., Bellefonte, PA, U.S.A.)/PDMS (CAR/PDMS) with 75-pm thickness. 

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... 

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