Extraction using supercritical carbon fraction

Essential oil recovered by traditional steam distillation contains 5-10% of the hallucinatory compound, myristicin. Nguyen et al. (1998) reported that extraction using supercritical carbon dioxide yielded a volatile fraction containing less myristicin. 

Shen Z, Palmer MV, Ting SST and Fairclough RJ. 1997. Pilot scale extraction and fractionation of rice bran oil using supercritical carbon dioxide. J Agric Food Chem 45(12) 4540-4544. 

Two PMMA-g-PDMS copolymers were also prepared with roughly similar composition (20 wt% and 26 wt% PDMS) and with the same molecular weight PDMS grafts (M = 10,000) by free radical polymerization and by anionic polymerization. The copolymers were first extracted of any unincorporated methacryloxy-terminated PDMS using supercritical carbon dioxide then they were fractionated with supercritical chlorodifluoromethane. Each fraction was characterized in the same manner as described for the three polymers depicted in figure 9.15 and the results are shown in figure 9.16 (DeSimone et al., 1990). The differences in chemical composition distribution profiles of the copolymers... 

Barca, L., P. Altieri, and S.G. Rossi A preliminary smdy for extracting from tobacco some groups of compounds which might be precursors of some components, mainly of the neutral smoke fraction, by using supercritical carbon... 

Castro-Vargas, H.L, Rodriguez-Varela, L.I., Ferreira, S.R.S., and Parada-Alfonso, F. 2010. Extraction of phenolic fraction from guava seeds (Psidium guajava L.) using supercritical carbon dioxide and co-solvents. J. Supercrit. Fluid 51 19-24. 

We have demonstrated in this paper that two and four samples can be extracted in parallel with supercritical carbon dioxide without significant impact on data quality. Modifications made to an off-line extractor involved addition of a multiport manifold for the distribution of supercritical fluid to four extraction vessels and of a 12-port, two-way switching valve that allowed collection of two fractions per sample in unattended operation. The only limitation that we have experienced with the four-vessel extraction system was in the duration of the extraction. When working with 2-mL extraction vessels and 50-/zm restrictors, and using the pressure/temperature conditions mentioned above, the 250-mL syringe pump allows us a maximum extraction time of 60 min. During this time, two 30-min fractions can be collected with the present arrangement. 

Nguyen, LJ., Anstee, M. and Evans, D.A. (1 998) Extraction and fractionation of spices using supercritical fluid carbon dioxide. Presented at The 5th International Symposium on Supercritical Fluids, Nice, France. 

The possibility of CB fractionation with supercritical carbon dioxide (SC-C02) has not yet been fully explored. Coenen Kriegel [7] claimed that fats can be fractionated using SC-C02 without giving examples. Rossi et al. [8] only observed minor changes in the triacylglycerol compositions of fats extracted from cocoa nibs and shells as a function of time, temperature and pressure. A real fractionation of the fat, however, was not achieved. 

Usually, the terpenes are removed from the cold-pressed oils (deterpenation) to concentrate the flavour fraction, thus resulting in a more stable product with improved solubility in the alcoholic solvents used in food and perfume processing. Supercritical carbon dioxide extraction appears as a promising and alternative technique to refine cold-pressed citrus oils [1,2, 3). Potentially, it has the advantages that it can be carried out at mild temperatures, provides better yields and leaves no solvent residues. 

The fatty acid composition of the extracts was not affected by temperature, pressure, and the extraction method (Table 4). Supercritical carbon-dioxide-extracted oil samples had similar fatty acid composition to that of the Soxhlet-extracted oil (Table 4). All of the wheat germ extracts consisted of about 56% linoleic acid (18 2 n-6), which is an essential fatty acid (Table 4). The total unsaturated and polyunsaturated fatty acid (PUFA) content of the wheat germ oil was about 81 % and 64%, respectively. The SC-CO2 extraction of wheat germ resulted in extracts with similar tocopherol and tocotrienol compositions to those of the Soxhlet extracts (Table 8) (50). These results indicate that SC-CO2 technology can be used for extraction and fractionation of WGO components to obtain products with high quality. 

More than one hundred years ago, certain fundamental principles in supercritical extraction had already been known, but viable processes for using this technique developed slowly. In the past two decades, process engineers in several industries have been interested in using supercritical fluids to extract soluble nonvolatile components from mixtures. One of many examples is enhanced oil recovery using carbon dioxide. Another is the fractionation of cod-liver oil using supercritical ethane (1). 

Supercritical carbon dioxide has been industrially used in a variety of processes, including coffee decaffeination, tea decaffeination, and extraction of fatty acids from spent barley, pyrethrum, hops, spices, flavors, fragrances, com oil, and color from red peppers. Other applications include polymerization, polymer fractionation, particle formation for pharmaceutical and military use, textile dyeing, and cleaning of machine and electronic parts. 

The use of critical fluids for the extraction and refining of components in natural products has now been facilitated for over 30 years. Early success in the decaffeination of coffee beans and isolation of specific fractions from hops for flavoring beer, using either supercritical carbon or liquid carbon dioxide, are but two examples of the commercial application of this versatile technology. Critical fluid technology, a term that will be used here to embrace an array of fluids under pressure, has seen new and varied applications which include the areas of engineering-scale processing, analytical, and materials modification. 

The monofunctional and difunctional compounds can be separated with supercritical carbon dioxide at 165 bar (2,400 psia) and 60°C. Although the difference in vapor pressure between the two compounds is not great enough to allow facile separation by distillation, supercritical carbon dioxide is able to separate these compounds, which differ by only one methacryloxy group. Figure 9.54a, b are HPLCs of the two fractions obtained from the extraction. The same scale that is used for the HPLC of the parent solution is drawn on... 

Previous reports 30, 31) have appeared on the use of siqiercritical fluid extraction (SFE) coupled with siqrercritical fluid fractionation (SFF) for the enrichment of these FPE. Carbon dioxide (CO2) and ethanol (EtOH), as a cosolvent, were utilized to fiactionate and eruich the FPE from 1.2S to 14.5 wt% in com bran oil employing a sorbent bed. However, this prior research was performed on an analytical scale. In the present study, SFF technology of com bran oil has been sc ed up using SFE/supercritical fluid chromatogr hy (SFE/SFC). The oil is remov from the com bran 1 utilizing supercritic carbon dioxide (SC-CO2), and then the extract is fiactionated by on-line SFC to obtain a fraction enriched in FPE. 

We were anxious to evaluate the use of supercritical carbon dioxide (scCOj) to remediate an urban soil. A two-stage approach was prompted by our efiforts to make the process continuous. SCCO2 extraction of particulate media is inherently a batch process. Pressure within the extractor is maintained with a capillary restrictor (in our case a 50 pm diameter silica tube) that is prone to fouling. The non-polar organic Section of an aqueous (surfactant) extract can be removed continuously (either on site or off site) with scCOj in a counter current liquid-liquid like process. The heavy metal contaminants remain with the water fraction for subsequent treatment. The organics fraction is the subject of this short review on SCCO2 processing. 

Some simple material balance considerations permit the maximum achievable EPA concentration to be calculated using the data shown in Table III which gives the composition of the codfish oil esters that were tested by Eisenbach. As is calculated from the values given in the table, the C20 fraction comprises 26.7% (w/w) of the feed stock, and the C20 5 (EPA) component comprises 54.7% of the C20 s. Since to a first approximation supercritical extraction separates by carbon number, i.e., by the length or molecular weight of the fatty acid ester, the data in Table III show that the theoretical maximum EPA concentration achievable is 54.7% if the C20 s could be separated into a fraction containing only C20 s, the EPA concentration in that fraction would be 54.7%. Eisenbach obtained a C20 fraction of 96.3% in a two pass system which is an excellent value it is calculated that the EPA concentration in that fraction is 52.7%, also an excellent value relative to the theoretical value of 54.7%. 

Nilsson, W.B., Gauglitz, E.J., and Hudson, J.K. (1989) Supercritical fluid fractionation of fish oil esters using incremental pressure programming and temperature gradient, J. Am. Oil Chem. Soe. 66, 1596-1600. Higashidate, S., Yamauchi, Y., and Saito, M. (1990) Enrichment of eicosapentaenoic acid and docosahexaenoic acid esters from esterified fish oil by programmed extraction-elution with supercritical carbon dioxide, J. Chromatogr. 515,295-303. 

Recently, there has been an increasing interest in the use of supercritical fluid extraction (SEE) with carbon dioxide (CO2) as a solvent. This process uses the properties of gases above their critical points to extract selective soluble components from a raw material. Carbon dioxide is an ideal solvent for the extraction of natural products because it is nontoxic, nonexplosive, readily available, and easy to remove from extracted products [3,6]. SFE has the abihty to use low temperatures, leading to less deterioration of the thermally labile components in the extract. In addition, SFE is typically carried out in the absence of air which also ensures minimal alteration of the active ingredients and preservation of the curative properties [46, 47]. SC CO2 is generally efficient in the purification and fractionation of hydrophobic compounds, such as flavonoids and cinnamic acid derivatives from plant matrixes [49]. 

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