Commercial Polydimethylsiloxane Fiber Research Articles

Silver-based polymeric ionic liquid sorbent coatings for solid-phase microextraction: Materials for the selective extraction of unsaturated compounds

A new generation of silver-based polymeric ionic liquid (PIL) sorbent coatings has been developed and applied in solid-phase microextraction (SPME). The new materials are based on ionic liquid monomers formed by cations containing the silver(I) ion coordinated with two 1-vinylimidazole ligands. Up to seven different silver-based PIL sorbent coatings were developed by polymerizing the silver-IL monomer in the presence of either silver bis[(trifluoromethyl)sulfonyl]imide, and/or a dicationic ionic liquid crosslinker. The obtained sorbent coatings were found to possess adequate thermal stability despite the presence of the silver(I) ions. Thermal desorption of the analytes at 175 °C was effectively used without any significant decrease in extraction efficiency. The developed sorbent coatings were used in two different applications: the determination of alkenes/alkynes via headspace SPME and the determination of unsaturated fatty acids using direct-immersion SPME. In the former approach, the silver-based PILs were particularly selective for the determination of unsaturated compounds with terminal double bonds such as 1,5-hexadiene, 2-methyl-1,5-hexadiene, and 1,8-nonadiene. A study of the extraction mechanism of the analytes to the sorbent coating revealed a competitive partitioning of the analytes. In the second approach, the most selective silver-based PILs were applied for the determination of oleic acid, linoleic acid, and linolenic acid. After proper optimization of the method, the coatings were found to be more or as sensitive as the commercial polydimethylsiloxane fiber. Limits of detection between 2.6 and 8.2 μg L−1 in ultrapure water and from 12 to 14 μg L−1 in tap water were obtained for the best silver-based PIL, with relative standard deviations lower than 13% in all cases at a spiked level of 160 μg L−1. Finally, the fiber was effectively applied for the analysis of rinse water from a dairy farm, with adequate detection of the analytes at concentrations between 52 and 179 μg L−1.

Determination of fatty acids in soil samples by gas chromatography with mass spectrometry coupled with headspace solid-phase microextraction using a homemade sol-gel fiber.

Through the use of a homemade sol-gel-derived fiber, a headspace solid-phase microextraction technique coupled to gas chromatography with mass spectrometry was developed for the determination of fatty acids with long, even-numbered carbon chains (C12 -C24 ) in soil samples. The experimental parameters such as reaction time, temperature, and ionic strength that might affect derivatization, extraction, and desorption were investigated. Under the optimized conditions, the linearity of the method ranged from 0.1 to 100mg/L with a correlation coefficient >0.997. The limit of detection values based on a signal-to-noise ratio of 3:1 were determined with the concentration from 0.39 to 39.4μg/L. The recoveries of the method for the soil samples were from 91.15 to 108.1%. This developed method using a homemade fiber showed a higher sensitivity than that using a commercial polydimethylsiloxane fiber and was also for the analysis of real soil samples from the Paomaling geological park of China.

Development of a highly robust solid phase microextraction fiber based on crosslinked methyl methacrylate–polyhedral oligomeric silsesquioxane hybrid polymeric coating

A novel solid-phase microextraction (SPME) fiber was prepared by polymerization of an organic–inorganic hybrid polymeric coating on an anodized and derived Ti wire, and applied for the analysis of polycyclic aromatic hydrocarbons from environmental samples followed by high performance liquid chromatography (HPLC) analysis. A polyhedral oligomeric silsesquioxane (POSS) reagent containing methacryl substituent groups was used as an organic–inorganic hybrid cross-linker, and copolymerized with methyl methacrylate (MMA) to fabricate the hybrid coating via thermally initiated free radical polymerization in a glass capillary mold. The prepared fiber can be easily withdrawn from the glass capillary mold by controlling the polymerization conditions, especially polymerization solvent. A homogeneous and porous coating with thickness of about 100μm was achieved using ethanol as polymerization solvent at the mass ratio of MMA to POSS as 1:0.5. High chemical and mechanical stability, as well as excellent durability for more than 100 times extractions with almost undiminished extraction efficiency were achieved due to the chemical immobilization and crosslinked hybrid coating. The proposed fiber showed much better extraction performance than the 100μm commercial polydimethylsiloxane fiber for extracting PAHs from aqueous sample. The developed SPME-HPLC method for the determination of PAHs using the MMA–POSS hybrid coating achieved good linearity with good correlation coefficients (R=0.991–0.999) and low detection limits in the range of 0.006 to 0.05ngmL−1 (S/N=3). The proposed fiber was successfully applied to the extraction of PAHs from environmental water samples with recoveries of 82–104% for river water, 83–103% for pool water, and 79–98% for wastewater, respectively.

Electrochemical preparation of polyaniline–ionic liquid based solid phase microextraction fiber and its application in the determination of benzene derivatives

A polyaniline–ionic liquid (i.e. 1-butyl-3-methylimidazolium tetrafluoroborate, [C4mim][BF4]) composite film coated platinum wire (PANI–IL/Pt) was prepared by electrochemical method for the first time. Scanning electron microscopy image showed that the PANI–IL composite film was even and porous. When the PANI–IL/Pt was used as a fiber for the headspace solid-phase microextraction (HS-SPME) of some benzene derivatives (i.e. 1,3-dimethylbenzene, 1,2-dimethylbenzene, 1,4-dichlorobenzene, 1,2-dichlorobenzene, 1,3,5-trimethylbenzene and 1,2,4-trimethylbenzene), followed by gas chromatographic analysis, it presented excellent performance, which was much better than that of PANI/Pt and commercial polydimethylsiloxane fiber. Hence the fiber was coupled with gas chromatography for the determination of these benzene derivatives. It was found that under the optimized conditions the linear ranges were 0.04–400μgL−1 with correlation coefficients above 0.99, the detection limits were 9.3–48.1ngL−1 (S/N=3), the relative standard deviations (RSDs) were smaller than 5.1% for five successive measurements with single fiber, and the RSDs for fiber-to-fiber were 5.0–11.1% (n=3) for different benzene derivatives. The proposed method was successfully applied to the extraction and determination of benzene derivatives in waste water and tap water, and the recoveries were 87.1–108.1% for different analytes. Therefore, the PANI–IL/Pt is a promising SPME fiber.

Polymeric ionic liquids as selective coatings for the extraction of esters using solid-phase microextraction

A new class of stationary phase coatings for solid-phase microextraction (SPME) based on polymeric ionic liquids (PILs) is presented. PIL-based SPME coatings exhibit exceptional film stability, high thermal stability, reproducible extraction efficiencies, and long lifetimes. A series of three homologous polymeric imidazolium-based ionic liquid coatings were synthesized by free radical reaction. The fiber coatings were used to extract esters and fatty acid methyl esters from aqueous solution followed by gas chromatographic separation and flame ionization detection. To examine the effect of the matrix on the coatings, extractions were carried out in a synthetic wine solution followed by recovery experiments in two real wine samples. When carrying out the extractions in aqueous solution, the detection limits for most analytes ranged from 2.5 to 50 μg L −1 whereas lower detection limits were obtained for larger fatty acid methyl esters. Recovery experiments carried out in red and white wines ranged from 70.2% to 115.1% using the PIL fibers compared to 61.9% to 102.9% using a commercial polydimethylsiloxane fiber of similar film thickness. The structural tuning capability of these new coating materials makes them widely amendable to performing task-specific microextractions.

Investigation of solid-phase microextraction efficiency using pencil lead fiber for in vitro and in vivo sampling of defensive volatiles from insect's scent gland

A new in vitro and in vivo solid-phase microextraction (SPME) sampling method using pencil lead fiber coupled with gas chromatography was developed for a fast, easy and reliable monitoring and recognition of volatile defensive chemical of scent gland of Graphosoma Lineatum (L.) ( Heteroptera Pentatomidae). The efficiency of three methods: (1) in vitro surgical sampling and direct injection in GC analysis known as a classical method, (2) in vitro surgical sampling, SPME/GC analysis and (3) in vivo SPME/GC method were investigated. The efficiency and reliability of homemade pencil lead fiber was evaluated and compared by commercial polydimethylsiloxane (PDMS) fiber. Some effective and experimental parameters, such as extraction time, chromatographic conditions were examined and optimized. The obtained results reveal that the in vivo SPME/GC is much better than in vitro pentane extraction of volatile compounds followed by either headspace SPME or direct injection and GC analysis. From the results obtained, for the studied chemicals, the extraction capacity of pencil lead fiber is about 1000-fold more than commercial PDMS fiber.