Supercritical fluid extraction for

Adsorption and Desorption Adsorbents may be used to recover solutes from supercritical fluid extracts for example, activated carbon and polymeric sorbents may be used to recover caffeine from CO9. This approach may be used to improve the selectivity of a supercritical fluid extraction process. SCF extraction may be used to regenerate adsorbents such as activated carbon and to remove contaminants from soil. In many cases the chemisorption is sufficiently strong that regeneration with CO9 is limited, even if the pure solute is quite soluble in CO9. In some cases a cosolvent can be added to the SCF to displace the sorbate from the sorbent. Another approach is to use water at elevated or even supercritical temperatures to facilitate desorption. Many of the principles for desorption are also relevant to extraction of substances from other substrates such as natural products and polymers. 

Braga et al. ° compared the efficiencies of several processes, i.e., hydrodistillation, low pressnre solvent extraction, and Soxhlet and supercritical fluid extraction. For each process, the inflnences of several parameters (duration, temperature, nature of solvent) were also evalnated. These authors concluded that the Soxhlet method performed with ethanol/isopropanol 1/100 v/v for 2 hr and 30 min was the most effective. Snn et al. nsed solid phase extraction to concentrate (nine times) a... 

Lin JG, Arunkumar R, Liu CH (1999) Efficiency of supercritical fluid extraction for determining 4-nonylphenol in the municipal sewage sludge. J Chromatogr A 840 71-79... 

Alzaga R, Bayona JM, Barcelo D. Use of supercritical fluid extraction for pirimi-carb determination./. Agric. Food Chem. 1995 43 395 400. 

Cal et al. [85] carried in situ derivativisation and supercritical fluid extraction for the simultaneous determination of butyltin and phenyltin compounds in sediments. 

R Marsili, D Callahan. Comparison of a liquid solvent extraction technique and supercritical fluid extraction for the determination of a- and /8-carotene in vegetables. J Chromatogr Sci 31 422-428, 1993. 

The adaptation of supercritical fluid extraction (SFE) in routine residue and metabolism analysis as well as other extraction/separation laboratories and applications has been slow. This is despite the demonstrated feasibility of using SFE for the removal of sulfonylureas, phenylmethylureas and their metabolites from soil and plant materials (1-2), as well as widespread demonstrated use of supercritical fluid extraction for other applications (3-6). The reason for this is simple. Although automated, SFE extraction apparatus typically only analyzes a single sample at a time. The technique could not compete effectively with the productivity of an experienced technician performing many sample extractions simultaneously. In essence, with a one vessel automated supercritical fluid extractor, operator attendance is high and throughput is about the same or even less than current conventional liquid-liquid and solid-liquid extraction techniques. 

Applications of Supercritical Fluid Extraction for the Extraction of Alkaloids 418... 

APPLICATION OF SUPERCRITICAL FLUID EXTRACTION FOR THE EXTRACTION OF ALKALOIDS... 

D. L. Allen, K. S. Scott and J. S. Oliver, Comparison of sohd-phase extraction and supercritical fluid extraction for the analysis of morphine in whole blood , J. Anal. Toxicol. 23 216-218 (1999). 

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). 

Szekely, E., Simandi, B., Illes, R., Molnar, P., Gebefugi, I., Kmecz I., and Fogassy, E. Application of supercritical fluid extraction for fractionation of enantiomers, J. Supercritical Fluids 2003, accepted for publication. 

Bjorklund, E., L. Mathiasson, P. Persson, et al. 2001. Collection capacity of a solid phase trap in supercritical fluid extraction for the extraction of lipids from a model fat sample. J. liquid Chromatogr. Rel. Technol. 24 2133-2143. 

Alexandrou N, Pawliszyn JB. 1990. Supercritical fluid extraction for the rapid determination of polychlorinated dibenzo-p-dioxins and dibenzofurans in municipal incinerator fly ash [Abstract]. New York, NY 41st Pittsburgh Conference and Exposition on Analytical Chemistry and applied chemistry. 

In our institute a novel method is under development to integrate mediated electrooxidation and supercritical fluid extraction for synthesis of organic compounds. Figure 2 shows the principle of this combination... 

Supercritical fluid extraction (SFE) is a suitable process for many separation problems. The regeneration of the supercritical fluid is as important as the extraction step itself Therefore this paper presents a method to do this in a more isobaric way than the customary pressure reduction regeneration. For the example of soil remediation we have investigated the activated carbon regeneration of supercritical carbon dioxide loaded with the low-volatile polycyclic aromatic hydrocarbon (PAH) pyrene. Characteristics of supercritical fluid extraction for soil remediation are elevated temperatures and pressures up to 370 K and 300 bar. For this reason adsorption isotherms of pyrene on activated carbon up to these conditions are measured first. Subsequently this method is used to regenerate carbon dioxide in a closed solvent cycle plant with a 4 1 extractor. An economic analysis using these results indicate that the soil remediation costs will decrease for about 20 - 30 % by means of an activated carbon adsorber. 

Application of Supercritical Fluid Extraction for Spices and Herbs with Pressures up to 800 bar... 

Morrison, J.F., MacCrehan, W.A., Selavka, C.M., Evaluation of supercritical fluid extraction for the selective recovery of drugs of abuse from hair, 2nd International Meeting on Clinical and Forensic Aspects of Hair Analysis, National Institute on Drug Abuse. Special Publication, submitted, 1995. Welch, M.J., Sniegoski, L.T., Allgood, C.C., Habram M., Hair analysis for drugs of abuse evaluation of analytical methods, environmental issues, and development of reference materials, /. Anal. Toxicol, 17(6), 389-398, 1993. 

The same team, Sedlakova et al. (2003 a), has investigated the application of Supercritical Fluid Extraction for the essential oil determination in small samples gathered during breeding as an alternative method. The results were used as a one of the criteria during breeding. Classical way of the essential oil determination does not allow this option. Table 6 shows the essential oil content in Czech varieties and different essential oil composition of some European caraway resources is mentioned in table 7. 

The supercritical fluid extraction, for example - the use of supercritical CO2 as the extracting solvent in place of organic solvents is becoming popular. The supercritical CO2 has the following advantages non-toxic, environmentally friendly, cheap, non-flammable and applicable on large scales [38]. The intrinsic mechanisms involved in the increased solubility of solute at supercritical conditions [39] as well as the enhancement effect imposed by the catalytic amounts of water[40] known as entrainer effect are studied. 

Karlsson L, Torstensson A, Taylor LT. The use of supercritical fluid extraction for sample preparation of pharmaceutical formulations. J Pharm Biomed Anal 1997 Feb 15(5) 601-611. 

Veress T. Sample preparation by supercritical fluid extraction for the HPLC determination of cannabinoids. LC-GC Int 1997 10 114 122. 

Hawthorne SB, Riekkola MF, Srenius K, Holm Y, Hiltunen R, Hartonen K. Comparison of hydrodistillation and supercritical fluid extraction for the determination of essential oils in aromatic plants. J Chromatogr 1993 634 297-308. 

Khundker S, Dean JR, Jones P. A comparison between solid phase extraction and supercritical fluid extraction for the determination of fluconazole from animal feed. J Pharm Biomed Anal 1995 13 1441-1447. 

Turner C, Mathiasson L. Determination of vitamins A and E in milk powder using supercritical fluid extraction for sample clean-up. J Chromatogr 2000 ... 

Allen DL, Oliver JS. The use of supercritical-fluid extraction for the determination of amphetamines in hair. Forensic Sci Int 2000 107 191-199. 

Howard AL, Shah MC, Ip DP, Brooks MA, Strodelll JTB, Taylor LT. Use of supercritical-fluid extraction for sample preparation of sustained-release felo-dipine tablets. J Pharm Sci 1994 83 1537-1542. 

N. Alexandrou and J. Pawliszyn, Supercritical Fluid Extraction for the Rapid Determination of Polychlorinated Dibenzo-p-Dioxins and Dibenzofurans in Municipal Incinerator Fly Ash, Paper No. 548, The Pittsburgh Conference and Exposition on Analytical Chemistry and Applied Spectroscopy, New York, New York, March 1990. 

Although Francis studied solubility behavior in liquid carbon dioxide (at approximately 25°C, 66 bar (950psia)), his results are very general. For example, a compound that is soluble in liquid carbon dioxide will also be soluble in supercritical carbon dioxide. The level of solubility, which can be more or, in fact, less than that found in liquid CO2, will depend on the operating region in P-T-x space. Thus, the data of Francis can be used to assess the potential of supercritical fluid extraction for many separations before any experimental work is carried out. The importance of Francis s contribution cannot be overemphasized. 

The potential for achieving a lower-energy process also motivated a substantial effort to examine supercritical fluid extraction for separating acetic acid from water. The work falls into two subcategories separation of fermentation-... 

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