C Supercritical Fluid Extraction

Careri M, Furlattini L, Mangia A, Musci M, Anklam E, Theobald A and von Holst C, Supercritical fluid extraction for liquid chromatographic determination of carotenoids in Spirulinapacifica algae A chemometric approach. J ChromatogrA 912 61-71 (2001). 

Drews M J, Ivey K and Lam C, Supercritical fluid extraction as an alternative to the Soxhlet extraction of textile materials . Textile Chem. Color., 26(10), 29, 1994. 

Polesello S, Lovati F, Rizzolo A, Rovida C. Supercritical-fluid extraction as a preparative tool for strawberry aroma analysis. J High Resolut Chromatogr 1993 16 555-559. 

Motohashi, N., Nagashima, H., and Parkanyi, C., Supercritical fluid extraction for the analysis of pesticide residues in miscellaneous samples, J. Biochem. Biophys. Methods, 43, 313-328, 2000. 

Ling, Y.C. Teng, H.C. Castwright, C. Supercritical fluid extraction and cleanup of organochlorine pesticides in Chinese herbal medicine. J. Chromatogr. A, 1999, 835 (1-2), 145-157. 

Villanueva et studied the pressurized liquid extraction (PLE) of thyme varieties (Thymus vulgaris. Thymus zygis and Thymus citriodorus) using ethanol, limonene, and ethyl lactate solvents, at different extraction temperatures (60, 130, and 200 C). Supercritical fluid extraction wifli pure CO2 (SFE-CO2) and with the three green solvents used as cosolvent were also tested. Additionally, the authors reported solubility data of thymol in limonene and ethanol at ambient pressure and temperatures in the range 30-43 C and the results were compared with efliyl lactate solubility data previously reported. In this respect, it was observed that thymol is very soluble in the three solvents, particularly in ethanol, followed by efliyl lactate, with concentrations around 90 wt% at the highest studied temperature. On the contrary, the solubility of thymol in limonene is somewhat lower ( 73 wt%). 

X. Lou, H.-G. Janssen and C. A. Cramers, Investigation of pai ameters affecting the online combination of supercritical fluid extraction with capillai y gas cliromatogi aphy , J. Chromatogr. 750 215-226 (1996). 

M. C. Tavai es and P. M. Lan as, On-line coupling of supercritical fluid extraction with supera itical fluid cltromatogr aphy , 7. Braz. Chem. Soc. in press (2001). 

Figure 15.14 Separation of explosives exnacted from water by using SPE-SFE-GC at several SEE trapping temperatures, peak identification is as follows NG, nitroglycerin 2,6-DNT, 2,6-dinitrotoluene 2,4-DNT, 2,4-dinitrotoluene TNT, triniti otoluene IS, 1,3-tiichloroben-zene. Adapted Journal of High Resolution Chromatography, 16, G. C. Slack et al., Coupled solid phase extraction supercritical fluid extraction-on-line gas cliromatography of explosives from water , pp. 473-478, 1993, with permission from Wiley-VCH.

Henry, M.C. and Yonker, C.R., Supercritical fluid chromatography, pressurized liquid extraction, and supercritical fluid extraction. Anal. Chem., 78, 390, 2006. 

Bergeron, C. et al.. Comparison of the chemical composition of extracts from Scutellaria lateriflora using accelerated solvent extraction and supercritical fluid extraction versus standard hot water or 70% ethanol extraction, J. Agric. Food Chem., 53, 3076, 2005. 

Teng, W.Y., Chen, C.C., and Chung, R.S., HPLC comparison of supercritical fluid extraction and solvent extraction of coumarins from the peel of Citrus maxima fmit, Phytochem. Anal, 16, 459, 2005. 

Mantell, C., Martinez de la Ossa, E., and Rodriguez, M., Supercritical fluid extraction of anthocyanins from grape pomace, in Solvent Extraction for the 21st Century, Cox, M., Hidalgo, M., and Valiente, M., Eds., Barcelona, Spain, 1999. 

Supercritical fluid extraction (SFE) is a technique in which a supercritical fluid [formed when the critical temperature Tf) and critical pressure Pf) for the fluid are exceeded simultaneously] is used as an extraction solvent instead of an organic solvent. By far the most common choice of a supercritical fluid is carbon dioxide (CO2) because CO2 has a low critical temperature (re = 31.1 °C), is inexpensive, and is safe." SFE has the advantage of lower viscosity and improved diffusion coefficients relative to traditional organic solvents. Also, if supercritical CO2 is used as the extraction solvent, the solvent (CO2) can easily be removed by bringing the extract to atmospheric pressure. Supercritical CO2 itself is a very nonpolar solvent that may not have broad applicability as an extraction solvent. To overcome this problem, modifiers such as methanol can be used to increase the polarity of the SFE extraction solvent. Another problem associated with SFE using CO2 is the co-extraction of lipids and other nonpolar interferents. To overcome this problem, a combination of SFE with SPE can be used. Stolker et al." provided a review of several SFE/SPE methods described in the literature. 

Supercritical fluid extraction (SFE) is generally used for the extraction of selected analytes from solid sample matrices, but applications have been reported for aqueous samples. In one study, recoveries of 87-100% were obtained for simazine, propazine, and trietazine at the 0.05 ug mL concentration level using methanol-modified CO2 (10%, v/v) to extract the analytes, previously preconcentrated on a C-18 Empore extraction disk. The analysis was performed using LC/UV detection. Freeze-dried water samples were subjected to SFE for atrazine and simazine, and the optimum recoveries were obtained using the mildest conditions studied (50 °C, 20 MPa, and 30 mL of CO2). In some cases when using LEE and LC analysis, co-extracted humic substances created interference for the more polar metabolites when compared with SFE for the preparation of the same water sample. ... 

J.W. King and K.S. Nam, Coupling enzyme immunoassay with supercritical fluid extraction, in Immunoassays for Residue Analysis, ed. R.C. Beier and L.H. Stanker, American Chemical Society, Washington, DC, Chapter 34, pp. 422-438 (1996). 

L.G. RandaU, W.S. Miles, F. Rowland and C.R. Knipe, Designing a Sample Preparation Method Which Employs Supercritical Fluid Extraction (SFE), Hewlett-Packard Publ. 435091-2102E, Wilmington, DE (1994). 

On-line SFE-GC finds use especially in petroleum-related applications [54], but has also been applied to polymer additives [47,55]. PBT polymers were extracted at 200 bar and 55 °C for the determination of carbonic acid diphenyl esters and other volatiles, using on-line SFE-GC-MS [47]. Extraction of entrained volatiles is a quality test for some polymers. SFE-GC-FTIR-MS has been employed to reveal the cause of odour of a smelly hose (a plasticiser) [56]. SFE-GC can also profitably be used for the determination of residual solvents in polymers such as benzene, toluene and o-xylene [57]. Oligomers of PE (up to 1000 Da) were determined by GC after supercritical fluid extraction [58]. 

Chiu K-L, Cheng Y-C, Chen J-H, Chang CJ and Yang P-W. 2002. Supercritical fluids extraction of Ginkgo ginkgoloides and flavonoids. J Supercrit Fluids 24 77—87. 

For the underlying science of supercritical fluids, try Steve Howdle s short article Supercritical solutions in Chemistry in Britain, August 2000, p. 23, which represents a useful introduction to the topic. For more applications of such fluids, try the short review article Some applications of supercritical fluid extraction , by D. P. Ndiomu and C. F. Simpson in Analytica ChimicaActa, 1988,213,237. The article is somewhat dated now but readable. A look at the contents list of The Journal of Supercritical Fluids will be more up-to-date go to http //www.umecheme. maine.edu/jsf. 

Lagenfeld et al. [48] studied the effect of temperature and pressure on the supercritical fluid extraction efficiencies of polyaromatic hydrocarbons and polychlorobiphenyls in soils. At 50°C raising the pressure from 350 to 650atm had no effect on recoveries. 

Snyder et al. [20] have compared supercritical fluid extraction with classical sonication and Soxhlet extraction for the extraction of selected pesticides from soils. Samples extracted with supercritical carbon dioxide modified with 3% methanol at 350atm and 50°C gave a =85% recovery of organochlorine insecticides including Dichlorvos, Endrin, Endrin aldehyde, p,p -DDT mirex and decachlorobiphenyl (and organophosphorus insecticides). 

Snyder et al. [94] compared supercritical extraction with classical sonication and Soxhlet extraction for the extraction of selected organophosphorus insecticides from soil. Samples extracted with supercritical carbon dioxide modified with 3% methanol at 350atm and 50°C gave a =85% recovery of Diazinon (diethyl-2-isopropyl-6-methyl-4-pyrimidinyl phosphorothiodate or 0,0 diethyl-0-(2-isopropyl-6-methyl-4-pyrimidyl) phosphorothioate). Ronnel (or Fenchlorphos) 0,0-dimethyl-0-2,4,5 trichlorophenol phosphorothiodate), Parathion ethyl (diethyl-p-nitrophenyl (phosphorothioate), Tetrachlorovinphos (trans,-2-chloro-l-(2,4,5 trichlorophenyl) vinyl (chlorophenyl-O-methylphenyl phosphorothioate) and Methiadathion. Supercritical fluid extraction with methanol modified carbon dioxide has been applied to the determination of organophosphorus insecticides in soil [260]. 

S.B. Hawthorne, C.B. Grabanski, E. Martin and D.J. Miller, Comparison of Soxhlet extraction, pressurized liquid extraction, supercritical fluid extraction and subcritical water extraction for environmental solids recovery, selectivity and effects on sample matrix. J. Chromatogr.A 892 (2000) 421 133. 

C. Turner, J.W. King and L. Mathiasson, Supercritical fluid extraction and chromatography for fat-soluble vitamin analysis. J. ChromatogrA 936 (2001) 215-237. 

J.Y. Shen, M.R. Kim, C.J. Lee, I.S. Kim, K.B. Lee and J.H. Shim, Supercritical fluid extraction of the fluoroquinolones norfloxacin and ofloxacin from orally heated chicken breast muscles. Anal. Chim. Acta 513 (2004) 451-455. 

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