Ethylene solid phase extraction

A monolithic hydrophobic polymer formed by photoinitiated polymerization for on-chip solid-phase extraction is shown in Figure 5.6. The polymer mixture includes butyl methacrylate (BMA) and ethylene dimethacrylate (EDMA), with the pore size controlled by the composition of the hexane/methanol porogenic mixture. The degree of pre-concentration depends on the flow rate, as shown in the pre-concentration of GFP at three flow rates (see Figure 5.7). The factors of pre-concentration were 355, 756, and 1002 for the flow rates of 3, 1.03, and 0.53 rE/min, respectively [342]. 

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. ... 

Qiang Gao, Dan Luo, Jun Ding, Yu-Qi Feng. (2010). Rapid magnetic solid-phase extraction based on magnetite/silica/poly(methacrylic acid-co-ethylene glycol... 

Solid-phase extraction is also often used to remove interfering coextracted compounds. Solid-phase extraction columns contain either non-polar reversed-phase Cig sorbents or polar sorbents (such as alumina, aminopropyl acid, and propylsulfonic acid). Matrix solid-phase dispersion cleanup using reversed-phase Cig material has been also employed for the determination of oxohnic acid in catfish muscle.In-tube solid-phase microextraction (SPME) based on poly(methacrylic acid-ethylene glycol dimethacrylate) (MAA-EGDMA) monolith coupled to high-preformance liquid chromatography (HPLC) with ultraviolet (UV) and fluorescence detection (FED) was... 

In another work lacosamide based MIPs of methacrylic acid monomers were used for the solid-phase extraction of the template from rat plasma before LC analysis and the results revealed a recovery of over 98% for the SPE and the LOD and LR of the method were evaluated to be 0.03 pg mL and 0.1-100 pg mL [244]. B. B. Prasad et al. reported the MIP-based SPE of epinephrine and detection of the same through an MIP based sensing device in plasma cerebrospinal fluids. They reported the reaction of functionalized multiwalled carbon nanotubes (MWCNTs-COCl)] as a monomer with N-hydroxy phenylmaleimide and used glycoldimethylacrylate as the cross-linking agent. The LOD of the hyphenated method was reported to be 0.002 ng mL [245]. In another study M. Moein and co-workers developed MIP cartridges to be used in combination with HPLC for facile analysis of human insulin in plasma and urine. They used insulin as the template, in the reaction between meth-acrylicacid monomer and ethylene eglycol dimethacrylate cross-linker. The reaction initiation was achived by 2,2/-azobisisobutyronitrile. The overal results showed LODs of 0.2 ng mL in plasma and 0.03 ng mL in urine with recovery factors over 87% [246]. 

Isotope fractionation between the vapor phase and the dissolved aqueous phase has been studied only for toluene and trichloroethylene (carbon only [545, 690]). Fractionation associated with adsorption has been quantified only for toluene in regard to sample extraction using a poly(dimethylsilo-xane)-coated solid-phase microextraction fiber [373] and qualified for benzene, toluene, and ethylbenzene based on high-pressure liquid chromatography analyses of isotopically labeled and unlabeled compounds (carbon and hydrogen [692]). Isotope fractionation associated with the reductive dechlorination of chlorinated ethylenes by zero-valent iron and zinc has been... 

Binary explosives are used primarily where only limited quantities are required or when a need for explosives cannot be anticipated. Because they are not considered as explosives until mixed, they can be safely stored and transported. A liquid-liquid type, PLX, was developed for minefield clearing and is composed of nitromethane sensitized with ethylene diamine. Commercial binary explosive products include Astrolite, based on hydrazine and NH4NO3. Astrolite was offered in both aluminized and non-aluminized formulations, the former advertised as the most powerful chemical explosive available. A more widely sold binary, Kinestik, combines finely pulverized NH4NO3 and nitromethane. This combination, offered by several vendors, is the only binary explosive currently available commercially. To ensure complete migration of the liquid into the solid phase, a dye is added to the liquid. When the intact mixed explosive is examined, dye can be extracted from the solid with acetone, examined by TLC or GC-MS, and compared to the dye used by producers of the product. Identification of the NH4NO3 is straightforward and nitromethane can be identified by low-temperature GC. 

A 10 mL round-bottomed flask was charged with (5)-6,6 -[oxybis(ethylene) dioxy]biphenyl-2,2 -diol (1) (98% ee, 225.6 mg, 0.78 mmol), quinine (127.0 mg, 0.39 mmol) and ethanol (2mL). The mixture was warmed until the mixture suspension turned to a clear solution, and was allowed to settle for 12 h. The solid residue [crystals of (5)-l-quinine complex] was collected by filtration. To a mixture of aqueous 1 M HCl and ether was added the obtained crystals of (5 )-l-qumine complex. This was stirred for 15 min at room temperature, and the solution was extracted with ether (twice). The combined organic layers were washed with brine, and dried over sodium sulfate. After concentration in vacuo, the residue was purified by silica gel flash column chromatography (hexane/ethyl acetate = 20/1-3/1) to give optically pure (5)-l (167.8 mg, 74%, 99% ee) as a colourless solid. The enantiomeric excess of (5)-l was determined by chiral stationary-phase HPLC analysis DAICEL CHIRALCEL... 

Kurnik and Reid described the solubility behavior for a number of binary solid mixtures consisting of combinations of phenanthrene, naphthalene, benzoic acid, and 2,3- and 2,6-dimethylnaphthalene extracted with supercritical carbon dioxide and ethylene. They found that for a binary solid mixture, the presence of one of the solid components solubilized in the SCF-rich phase enhances the solubility of the other solid component in the SCF-rich phase. They suggest that the first solid component acts as an entrainer, or so-called cosolvent, to enhance the solvent power of the pure SCF. For example, they... 

It is well known from theory and experiment that the interaction of ethylene with silver is nearly repulsive (711. This weak adsorption can be investigated with solid-state C NMR (72], and an illustration of such spectra for 1- C-C2H4 and 1, 2- C2 C2H4 is depicted in Fig. 36. The value extracted from the chemical shift/dipolar powder patterns of these spectra is 1.34 A. This result is close to the value of 1.335-1.340 A for ethylene in the gas phase (731, a bond distance that reflects the weak interaction between the silver and the adsorbed ethylene. 

Under the protection of nitrogen, the compound 2.2.30 (500 mg, 1.36 mmol) was dissolved in AcOH (10 mL), and then, Pb(OAc)4 (3.1 g, 6.8 mmol) was added at 0 °C. The reaction was stirred for 1 h at 0 °C. TEC showed that the reaction was completed. Ethylene glycol (5 mL) was added to quench the reaction. The solid was filtered off and washed with ethyl acetate (1(X) mL). The organic phase was reserved and washed with saturated sodium bicarbonate (3 x 50 mL). The water phase was extracted with ethyl acetate (3 x 50 mL). The combined organic phase was dried over anhydrous sodium sulfate. After filtration, the solvent was removed by a rotary evaporator, and the resulting crude product was isolated and purified by flash column chromatography (PE/EA = 5 1) to give 2.2.37 (275 mg) and 2.2.38 (135 mg) as white solid, total yield 92 %. 

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