Extraction by supercritical

The development of methods of analysis of tria2ines and thek hydroxy metabohtes in humic soil samples with combined chromatographic and ms techniques has been described (78). A two-way approach was used for separating interfering humic substances and for performing stmctural elucidation of the herbicide traces. Humic samples were extracted by supercritical fluid extraction and analy2ed by both hplc/particle beam ms and a new ms/ms method. The new ms /ms unit was of the tandem sector field-time-of-flight/ms type. 

Bonazzi et al. [18] reported the determination of miconazole and other imidazole antimycotics in creams by supercritical fluid extraction and derivative ultraviolet spectroscopic method. Cream based pharmaceuticals were mixed with celite and anhydrous sodium sulfate and extracted by supercritical fluid extractor (SFE) with... 

Beveridge THJ, Girard B, Kopp T and Drover JCG. 2005. Yield and composition of grape seed oils extracted by supercritical carbon dioxide and petroleum ether varietal effects. J Agric Food Chem 53(5) 1799-1804. 

Marrone C, Poletto M, Reverchon E and Stassi A. 1998. Almond oil extraction by supercritical CO2 Experiments and modeling. Chem Eng Sci 53(21) 3711-3718. 

Non-ionic surfactants of a commercial washing powder were separated by supercritical fluid chromatography (SFC) and determined by APCI-MS. The constituents were first extracted by supercritical fluid extraction (SFE) using C02 with or without methanol as a modifier. Variations of the conditions resulted in a selective extraction of the analytes, which could be determined without further purification. Six groups of surfactants were observed, four of which are alkyl-polyethoxylates. The presence of APEO could be excluded by identification recording SFC-FTIR (Fourier transform infrared) spectra [31]. 

Extraction by supercritical fluids, in particular carbon dioxide and propane, is currently being investigated as a means of controlling the size and shape of particles for inhalation. Supercritical fluids are liquids above their critical pressure and temperature [28]. Under these conditions the molecules exhibit the flow, polarity, and solvency properties common of liquids but have the diffusivities and reactivities characteristic of gases. 

An alternative to remove the residual solvent or monomer, respectively is the extraction by supercritical carbon dioxide. 

Supercritical drying (SCD) The wet cake of sol pillared bentonite (sol-PILB) was dispersed into absolute ethanol and filtrated, washed with ethanol for several times to replace the water by ethanol. The cake was transferred to a cartridge and the ethanol was extracted by supercritical fluid (CO2) for 3 h under 3000 psi, at 323 K. The flow rate was controlled around 2.5 ml/min. The sample was then calcined at 773 K for 12 h and labeled as sample SCD. 

Tocopherols consist of a, (3, y, and 8 isomers and are effective antioxidants. Oomah et al. (1997a) observed that y-tocopherol (9.04 mg/100 g seed) was the predominant isomer of Canadian flaxseed cultivars. Total tocopherol ( r = 0.42) and y-tocopherol (r = 0.41) values were correlated with seed oil content. Kamm et al. (2001) reported the distribution of tocopherols and tocotrienols in high and low linolenic flaxseed. Results were similar to the findings of Oomah et al. (1997a) in which y-tocopherol content was greater (430-575 mg/kg oil) in high ALA flaxseeds, whereas low linolenic flaxseed exhibited lower (170 mg/kg oil) values. Bozan and Temelli (2002) compared tocopherol levels in oil extracted by supercritical C02 fluid and soxhlet (Table XI). Soxhlet-extracted oil had greater tocopherol levels (76.4 mg/100 g oil). These authors speculated that the temperature-pressure combination may have influenced the tocopherol extraction by supercritical C02 fluid. 

Schurhammer, R., Bemy, F., Wipff, G. (2001), Importance of Interfacial Phenomena in Assisted Ion Extraction by Supercritical COy a Molecular Dynamics Investigation, Phys. Chem. Chem. Phys. 3, 647-656. 

Heaton et al. have reported the supercritical fluid chromatography of taxicin I and taxicin II extracted by supercritical fluid extraction of Taxu baccata, the English yew tree [41]. They compared capillary- and packed- column SFC and concluded that packed-column SFC was better than capil4 lary-column SFC for quantitative analysis of these compounds. Capillary SFC was done on either a biphenyl or carbowax column with unmodified carbon dioxide as the mobile phase. The packed-column SFC was performed on a nitrile column with a mobile phase consisting of a methanol gradient with carbon dioxide. 

Separation and purification of three turmerones, e.g. ar-turmerone, a- and P-turmerone, from turmeric oil extracted by supercritical carbon dioxide gave 71% purify by weight. Subsequently, purification using a normal-phase silica gel 60 column could separate and purify three major turmerones with 86% purify by weight of ar-turmerone and 81% purity by weight of a- and P-turmerone. These were identified by liquid-solid chromatography, NMR qualification and HPLC quantification, respectively (Li-Hsun Chang et al., 2006). 

Baumann, W., Rodrigues, S.V. and Viana, L.M. (2000) Pigments and their solubility in and extractability by supercritical C02. Part 1. The case of curcumin. Brazilian journal of Chemical Engineering 1 7, 323-328. 

The coke extraction by supercritical fluids is strongly dependent on the type of catalyst. The three-dimensional USYZ is easier accessible for the solvent than the two-dimensional ZSM-5 and the one-dimensional H-modernite. For USYZ there is an optimal temperature, at which the supercritical fluid has the highest ability for coke extraction. For ZSM-5 the coke content and the rest of the acid centres of catalyst are strongly dependent on the temperature. At 623 K the acid centres decreased only about 5%, but at 673 K they were almost totally decimated. Due to the faint coking tendency of ZSM-5 the supercritical fluid plays only a small role for the regeneration of the catalyst. But the supercritical fluid can ameliorate the product distribution of the EBD on ZSM-5. For H-mordenite the conversion of EB is strongly dependent on the temperature in the range of 623 - 673 K because of its one-dimensional channel system. 

One promising way to seperate halogenated flame retardents out of polymer composites seems to be the extraction by supercritical fluids like C02.. Main objective of this paper is to find the suitable conditions for high extraction efficiencies. For model mixtures involving the flame retardents TBBA, TBPA and HBCD the extraction efficiency from the inert matrix MgS04 was examined in relation to extraction pressure, temperature and time. The data form the basis for realistic tests on ABS composites with different flame retardents. 

As seen in Table 2 the PET-oligomers - mainly cyclic trimers - are not extracted by supercritical carbon dioxide at dyeing conditions. This was also confirmed by other authors [9], The surface content of oligomers depends on the dyeing temperature whereas the total amount of cyclic trimers does not change. 

As an alternative to traditional solvent extraction methods, the extraction by supercritical (SC) fluids has been used in tocol analysis. This is an environmentally friendly technique as little or no solvents are used. Extraction parameters, e.g. temperature and fluid density, are easily optimized and managed, and as the extraction is fast it is thus suitable for routine work with many samples. SC carbon dioxide has been used to extract tocols from barley (Fratianni et al, 2002), dried bay leaves (Gomez-Coronado et al, 2004), and garden cress seeds (Diwakar et al, 2010). Extractions were carried out in single or multiple steps and with different fluid densities controlled by extraction pressures. Tocol yields from barley were 5% and 14% less than by Soxhlet and chloroform-methanol extractions (Fratianni et al, 2002), yields from garden cress seeds were 26% less than by Soxhlet extraction (Diwakar et al, 2010), and a- and y-tocopherol yields from dried bay leaves were 22% and 40% less than by acetone extraction (Gomez-Coronado et al, 2004). Despite lower recoveries of tocols, the SC carbon dioxide extraction methods were considered comparable to the classical extraction methods (Fratianni et al, 2002). 

Supercritical CO2 extraction methods were evaluated for a number of oilseeds in the 1980s. Corn germ extraction by supercritical CO2 was evaluated by ARS researchers in Peoria, IL. Methods for corn germ extraction using 100% supercritical CO2 were developed (10, 17) and patented (18). Others have demonstrated that addition of ethanol modifier (0 -10%) to supercritical CO2 can decrease the extraction time and improve the functionality of germ proteins (19). Although there are no technical barriers, extraction of com germ with supercritical CO2 is more costly than conventional extraction methods. 

Polynuclear Aromatic Hydrocarbons in Environmental Materials Extraction by Supercritical Fluid Extraction... 

Zhang L, Xiang ZM, Bi LJ, Xie ZZ, Chen L. Gas chromatographic-mass spectrometric determination of fragrant components of crimson glory fresh flowers extracted by supercritical carbon dioxide. Sepu 1996 14 438-440. 

PHN, ACE, PYR, CHY, B[a]P, and benzo[e]pyrene were separated in a 50 mM borate buffer (pH 9) containing a mixture of 20 mM neutral methyl-(3-cyclodextrin (M(3CD) and 25 mM anionic sulfobutylether-(3-cyclodextrin (SB(3CD) at 30 kV and 30°C. " B[a]P and benzo[e]pyrene were successfully resolved with the other compounds in under 11 min in a 50-cm effective length of capillary without micelles in the mobile phase. The system was also less sensitive to temperature and separation potential. LIE detection with excitation at 325 nm at 2.5 mW from a He/Cd laser coupled to an optical fiber allowed for detection limits in the sub ppb range. The method described above was applied to the analysis of contaminated soil that had been extracted by supercritical CO2 for 20 min at 120°C and collected in methanol/DCM. ° Of the 16 EPA PAH mixtures, eleven compounds were detectable in the low ppb range. Ten of the eleven detectable compounds were measured in the soil extract. When compared to RP-HPLC, CE values were slightly lower but only six compounds were detected by HPLC-FLD. No direct relationship between PAH molecular size, polarity, or volatility with migration order was observed and B[b]F/B[k]F isomers were readily separated. 

Sediments and biota. Several sample digestion procedures (mostly between 0.1 and 1 g of freeze-dried sample) can be apphed such as (1) enzymatic digestion with lipase and protease (2) digestion with TMAH or KOH-EtOH or NaOH in methanol-water with or without microwave oven assistance (3) digestion with HCl and NaCl aqueous solution, with addition of ethyl acetate and methanol (4) extraction by supercritical CO2 (5) extraction by acetic acid. Often these digestions and extractions are accompanied by simultaneous extraction into an organic (or different organic) solvent such as hexane, dichloromethane, acetic acid-tropolone in hexane, and tropolone in dichloromethane, methanol or diethyl ether. 

Detailed analytical methods were as previously described [18]. Gel permeation chromatography (GPC) and capillary columns were employed for the precise analysis of the products. After each reaction, residual products remaining within the catalyst and the reactor were extracted by supercritical n-hexane at 250 °C (10 °C higher than the reaction temperature) and 35 bar, with additional N2 pressure of 10 bar. The supercritical fluid extraction after the reaction was conducted for 1 h, after which the products were also determined by chromatography [19]. 

It was found that if the content of the hydrocarbons extracted by supercritical 2-methyl-butane were analyzed, no hydrocarbons other than C12 alkene (two isomers) were detected. It is clear that C12 alkene, derived from oligomerization reactions, deposited onto catalytic sites and deactivated the catalyst. More specifically, high molecular weight alkenes such as C12, which have high electron density, might combine strongly with Lewis acid sites inside... 

Ca. 3.5 g sediment were extracted by supercritical fluid extraction (CO2 and 20% methanol) after HCl addition. The extraction recovery for TBT (verified with a TBT-spiked sediment) was (82 + 6)%. Grignard derivatization was performed, using 2 mol L EtMgCl in tetrahydrofuran. Separation was by CGC (column of 30 m length, internal diameter of 0.25 mm, DB-5 as stationary phase, 0.1 pm film thickness He as carrier gas at 2 mL min injector temperature at 40 °C column temperature ranged from 40 to 290 °C). Detection was FPD (temperature of 225 °C). Calibration was carried out with butyltin chloride calibrants calibration graph and standard additions of tripropyltin as internal standard. 

Ca. 1 g sample was extracted by supercritical fluid extraction with CO2 and a mixture of acetic acid and 0.2% tropolone with hexane as solvent (pressure of 50 atm, temperature of 50 Q. Ethylation was carried out with 2 mol L ethylmagnesium chloride. TPeT was added as internal standard. Separation was by capillary GC (column of 30 m length, 0.25 mm internal diameter, DB-17 as stationary phase, 0.25 pm film thickness H2 as carrier gas at 5 mLmin N2 as make-up gas at 30 mLmin injector temperature of 250 °C column temperature ranging from 60 to 280 °C). Detection was by FPD (detector temperature of 300 °C). Recoveries were assessed by standard additions results were (82 4)% for DBT, (75 + 2)% for TBT and (65 + 3)% for TPhT. Calibration was by calibration graph and standard additions, using the calibrants provided by SM T. 

The application of and N.M.R. spectroscopy, gas chromatography (G.C.) and mass spectrometry (M.S.) in the separation and identification of alkanes extracted from fossil fuels is illustrated with three Turkish lignites (including one extracted by supercritical gas), coal tar and petroleum crude. Elution of hydrocarbons from a silica-gel column may be monitored by N.M.R. and molecular-sieve sub-fractionation into normals and branched/cyclics by G.C., together with... 

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