Supercritical fluid technologies solutions

A number of techniques are based on supercritical fluid technology. Three are of particular pharmaceutical interest, namely the supercritical antisolvent (SAS) system, the rapid expansion of supercritical solution (RESS) method, and the gas antisolvent (GAS) technique [126]. 

N. Bonnaudin, "A Solution for the Treatment of Wastewater from Food and Pharmaceutical Industries Hydrothermal Oxidation, Presented at The Role of Supercritical Fluid Technology in Pharmaceutical/Nutraceutical/Food Processing, Supermat Network Seminar, July 6-8, 2005 (www.univ-pau.fr/supermat/OP6.pdf). 

Kompella UB, Koushik K. Preparation of drug delivery systems using supercritical fluid technology. Crit Rev Ther Drug Carrier Syst 2001 18 173-199. Petersen RC, Matson DW, Smith RD. Precipitation of polymeric materials from supercritical fluid solution the formation of thin films, powders, and fibers. Polym Prepr (Am Chem Soc, Div Pol Chem) 1986 27 261-262. 

McClellan, A. K., E. G. Bauman, and M. A. McHugh. 1985. Polymer solution supercritical fluid phase behavior. In Symposium Proceedings on Supercritical Fluid Technology, ed. J. M. L. Penninger, M. Radosz, M. A. McHugh, and V. J. Krukonis, 161. Amsterdam Elsevier. 

Based on the polarity difference between CO2 and the interior of the micelles, w/c microemulsions have found many applications as extraction media. Furthermore, by modifying pressure and temperature, solvent quality may be changed and it becomes, therefore, possible to exert a real control over the extraction process uptake of solutes inside micelles may be varied. This may be of use for separations/extractions involving bio-chemicals and proteins. In conventional solvents their separation from the reaction medium can be quite complicated, involving tedious processes such as fluid-fluid extraction, decantation, chromatography column, filtration, precipitation. Use of supercritical fluid technology with extraction in reverse micelles seems advantageous for proteins (e.g. 19, 76). This process was also used for the extraction of metals (77-79) and more recently of copper from a filter paper surface (1). 

MC2 McClellan, A.K., Bauman, E.G., and McHugh, M.A., Polymer solution-supercritical fluid phase behavior, in Supercritical Fluid Technology, Elsevier Sci. Publ., Amsterdam, 1985, 162. 

I. Ijjvclt Scngcrs, J.M.H. Cl 991) niermcxJynamics of solutions near the solvent critical point, in Bruno, Th J. and lily, J.l (eds.). Supercritical Fluid Technology. CRC Press, Boca Raton, H., pp. 1-56. 

Levelt Sengers, J. M. H. (1991a) Thermodynamics of Solutions Near the Solvent s Critical Point. In Supercritical Fluid Technology, T. J. Bruno and J. F. Ely, Ed. CRC Press Boca Raton, pp 1-56. 

Knutson, B. L., D. L. Tomasko, C. A. Eckert, P. G. Debenedetti, and A. A. Chialvo 1992, Local density augmentation in supercritical fluid solutions A comparison between fluoresence spectroscopy and molecular dynamics results . In F. V. Bright and M. E. McNally (eds.) Supercritical Fluid Technology, ACS Symposium Series 4 8. Washington ACS, p. 60. 

A new approach in the 1990s was to use supercritical fluid technology to produce uniform particles to replace crystallization. Even though super critical fluids were discovered over 100 years ago, and the commercial plant was built over 20 years ago in the United States, it is only now that the technology is used for a number of pharmaceutical applications (2-5), so as to produce aspirin, caffeine, ibuprofen, acetaminophen, etc. One of the major areas on which the research and development of supercritical fluids is focused is particle design. There are different concepts such as rapid expansion of supercritical solution, gas antisolvent recrystallization, and supercritical antisolvent to generate particles, microspheres, microcapsules, liposomes, or other dispersed materials. 

JR Combes, KP Johnston, KE O Shea, MA Fox. Influence of solvent-solute and solute-solute clustering on chemical reactions in supercritical fluids. In FV Bright, MEP McNally, eds. Supercritical Fluid Technology Theoretical and Applied Approaches to Analytical Chemistry. ACS Symposium Series No. 488. Washington, D.C. American Chemical Society, 1992, pp 31 7. 

Besides the supercritical fluid extraction (SFE) for preparation of medicines and materials processing, supercritical fluid technology involves processes such as supercritical anti-solvent (SAS), rapid expansion supercritical solutions (RESS), rapid expansion of a supercritical solution into a liquid solvent (RESOLV), supercritical assisted atomization (SAA), impregnation and solution enhanced dispersion by supercritical CO2 (SEDS) that involves the supercritical fluid in drug processing to drug delivery systems. 

The high rate of pubhshed works and the nature of the supercritical phase show that the technology is promising in developing new solutions to serious diseases that currently lead the rank of causes of death and suffering. This chapter briefly reviews the application of supercritical fluid technology for human health, covering the application of extraction of bioactive compounds... 

Ibuprofen is a nonsteroidal anti-inflammatoiy drug (NSAID) used for pain relief due to the anti-inflammatory effects [56], however this drug has low solubility in aqueous solutions [57, 58], which implies involvement in negative absorption by the body. Then researchers are using supercritical fluid technology to overcome these drawbacks. Antonov et al., [59] studied the solubility of ibuprofen in supercritical CO2 by fourier transform infrared spectroscopy, moreover ibuprofen was also studied in supercritical impregnation processes polymers [60, 61], in theoretical RESS process [62, 63] and experimentally for micronization of particles with reductions from 45 pm to 2.85 pm [64], and formation of even smaller nanoparticles by RESOLV [65]. Furthermore, Molnar et al., [66] studied the enantioseparation of racemic ibuprofen in SFE and realized that the system pressure of the extraction is directly related to resolution efficiency. 

Nanocapsules act like a reservoir, which are called vesicular systems. They carry the active substance entrapped in the solid polymeric membrane or on their surfaces. The cavily inside contains either oil or water. A schematic diagram of Polymer Nanocapsules is shown in Fig. 9.2 [5], There are different methods that are used nowadays to prepare polymeric nanoparticles, such as nanoprecipitation (also termed as the solvent diffusion and solvent displacement method), solvent evaporation, dialysis, microemulsion, surfactant-free emulsion, salling-out, supercritical fluid technology, and interfacial polymerization [2]. Among these methods, nanoprecipitation is a fast and simple process, which does not require a pre-prepared polymer emulsion before the nanoparticle preparation. It produces a dispersion of nanoparticles by precipitation of preformed hydrophobic polymer solution. Under... 

Extraction from Aqueous Solutions Critical Fluid Technologies, Inc. has developed a continuous countercurrent extraction process based on a 0.5-oy 10-m column to extract residual organic solvents such as trichloroethylene, methylene chloride, benzene, and chloroform from industrial wastewater streams. Typical solvents include supercritical CO9 and near-critical propane. The economics of these processes are largely driven by the hydrophihcity of the product, which has a large influence on the distribution coefficient. For example, at 16°C, the partition coefficient between liquid CO9 and water is 0.4 for methanol, 1.8 for /i-butanol, and 31 for /i-heptanol. 

A third motivation for studying gas solubilities in ILs is the potential to use compressed gases or supercritical fluids to separate species from an IL mixture. As an example, we have shown that it is possible to recover a wide variety of solutes from ILs by supercritical CO2 extraction [9]. An advantage of this technology is that the solutes can be removed quantitatively without any cross-contamination of the CO2 with the IL. Such separations should be possible with a wide variety of other compressed gases, such as C2LL6, C2LL4, and SF. Clearly, the phase behavior of the gas in question with the IL is important for this application. 

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