• Analytical Science and Technology
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• v.10 no.2
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• pp.131-138
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• 1997

Supercritical Fluid Chromatography(SFC) has become a technique for solving problems that are difficult to be monitored by other chromatographic methods. However, the most widely used fluid, is no more polar than hexane. Polar samples which are difficult to be analyzed with pure supercritical $CO_2$ because of their high polarity can be separated by adding polar modifiers to supercritical $CO_2$. In this paper, a new method for monitoring the mobile phase composition in modified supercritical fluid chromatography was developed. The amount of water dissolved in supercritical $CO_2$ was measured by amperometric microsensor which is made of thin film of perfluorosulfonate ionomer(PFSI). The amount of water dissolved in supercritical $CO_2$ stayed constant for a much longer time than with a saturator column. With this new mixing device, we could get good resolutions for vitamins which are difficult to separate with pure $CO_2$.

• Analytical Science and Technology
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• v.10 no.5
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• pp.350-356
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• 1997

Supercritical Fluid Chromatography(SFC) has been developed as an analytical technique for the compounds that is difficult to analyze by conventional chromatography. Since supercritical fluid $CO_2$ is difficult to elute solutes with high polarity, modified supercritical $CO_2$, was used as a mobile phase. In conventional method, silica column which is saturated with modifier was used. However, with this method, we can not control the quantity of modifier. In this paper, we developed a new method which can control quantity of modifier mixed in supercritical fluid $CO_2$. The quantity of $H_2O$ mixed was measured with amperometric microsensor which was made by perflurosulfonate ionomer(PFSI) film. we have also obtained a good supercritical fluid chromatogram of PAH mixture by use of a modifier composition programming method.

• Journal of the Korean Ceramic Society
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• v.37 no.7
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• pp.625-631
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• 2000

In this study, the characteristics and sinterablities of TiO2 powders which were fabricated on sol-gel process and supercritical fluid process were examined. The powders fabricated on sol-gel process were amorphous. The particle size and shape were changed with the amount of water used for hydrolysis of titanium ethoxide. The powders were changed from amorphous to crystalline by heating at 400℃. The crystalline anatase TiO2 powders were directly prepared in ethanol supercritical fluid condition that temperature was 270±3℃ and pressure was 7.3 MPa. It's primary crystalline size was 20 nm and agglomerated as spherical shape whose size was 0.7∼1㎛. The powders prepared on sol-gel process were not sintered densely at 900℃ because of abnormal grain growth. However, the powders which prepared on supercritical fluid process were sintered densely at the comparatively low temperature of 800℃ by ideal growth of grain, which are fired at 900℃.

• Polymer(Korea)
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• v.28 no.6
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• pp.445-454
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• 2004

The requirement for a much finer line width circuits on semiconductors needs new developers such as supercritical fluid to prevent the collapse of the photoresist micro-patterns. The copolymers contain t-butyl methacrylate having an acid-cleavable t-butyl group and supercritical fluid $CO_2$ soluble perfluorinated decyl methacrylate segments. The supercritical fluid $CO_2$-philic properties of the photoresist changed to supercritical fluid $CO_2$-phobic properties after the deprotection reaction by exposure, which made the exposed resist insoluble in the supercritical fluid $CO_2$ developer. The synthesized copolymers containing more than 30% of perfluorinated decyl methacrylate were found to be soluble in supercritical fluid $CO_2$. The variation of film thickness before and after exposure was largest when the mole ratio of perfluorinated decyl methacrylate in the copolymer was 30%.

• Textile Coloration and Finishing
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• v.33 no.3
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• pp.141-146
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• 2021

Supercritical fluid has excellent dissolving power for various materials based on low viscosity and high diffusion coefficient and is used as solvents in various chemical processes. However, its industrial application can be very tricky because the design, especially the size of the supercritical apparatus, should be carefully chosen to optimize the cost and the production of supercritical fluidic state. And the first step of the supercritical fluid apparatus design is to choose the appropriate size of the reactor vessel to produce supercritical fluid above its critical pressure and temperature. Therefore, this study aims to analyze thermodynamic behaviors of dichloromethane based on ideal gas, van der Waals, Redlich-Kwong, Soave-Redlich-Kwong, and Peng-Robinson equations of state. The correlation between the volume and pressure of dichloromethane at 200℃ was revealed and it can be used to design the optimized size of the supercritical apparatus for industrial production.

• Journal of Korean Society of Forest Science
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• v.110 no.3
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• pp.431-439
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• 2021

The present study evaluated the antioxidant activity, skin wrinkle reduction, and whitening activity of Pinus koraiensiscone scale extracts made with three different solvents (ethanol, supercritical fluid, and a mixture of both). Total polyphenol content was 11.03 mg/g GAE in the supercritical fluid extractand 33.79 mg/g GAE in the 70% ethanol extract. Electron donating ability of 1,000 ㎍/mL extract was 13.60% in the supercritical fluid extract, 91.37% in 70% ethanol extract, and 71.62% in mixed solvent extract. SOD-like activities in 100 ㎍/mL extract using supercritical fluid, 70% ethanol, and mixed solvents were 16.49%, 21.84%, and 10.7%, respectively. The ABTS⁺ radical scavenging activities of 1,000 ㎍/mL extract were 38.19%, 80.23%, and 78.72%for supercritical fluid extract, 70% ethanol extract, and mixed solvent extract, respectively. Tyrosinase inhibitory activities in 1,000 ㎍/mL extract were 24.54%, 36.55%, and 15.23% for supercritical fluid extract, 70% ethanol extract, and mixed solvent extract, respectively. Elastase inhibitory activities in 1,000 ㎍/mL extract were 15.62%, 22.56%, and 26.64% for supercritical fluid extract, 70% ethanol extract, and mixed solvent extract, respectively. Skin astringent activity (81.23% with 5000 ㎍/mL extract) was only detected in the 70% ethanol extract. Supercritical fluid and mixed solvent extracts showed no such activity. Our analysis of Pinus koraiensiscone scale extracts show that the highest aggregate activity was found in the 70% ethanol extract, followed by mixed solvent and supercritical fluid extracts. Therefore, our results oppose the hypothesis stating supercritical extract has the highest total polyphenol content and antioxidant activity.

• The Korea Journal of Herbology
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• v.28 no.6
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• pp.95-100
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• 2013

Objectives : The purpose of this study was to investigate antiaging and antioxidant effects on cultured human skin fibroblast with supercritical fluid extracts of Dendropanax morbifera, Corni fructus and Lycii Fructus. Methods : Supercritical fluid extraction (SFE) technique was applied to extract from three medicinal plants including stem of Dendropanax morbifera, Corni fructus and Lycii Fructus. Antioxidant activity of extract was evaluated by two different assays as 2,2-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and super oxide dismutase (SOD) like activities. These extracts were tested for cell viability on HS68 skin fibroblast by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay. We investigated the effects of Ultraviolet-B irradiation on cytotoxicity, type 1 collagen, elastin level and oxidative damage in cultured human skin fibroblast (HS68). Recently, many studies have reported that elastin is also involved in inhibiting or repairing wrinkle formation, although collagen is a major factor in the skin wrinkle formation. Results : The extracts obtained dose-dependently increased the scavenging activity on DPPH radical scavenging activity and SOD like activity. The supercritical fluid extracts of complex herbal medicine showed low cytotoxicity as more than 100% cell viability in 100ppm/ml concentration. HS68 fibroblasts were survived 70% at $120mJ/cm^2$ UVB irradiation and treated tumor necrosis factor (TNF)-alpha. The levels of aging factors and cytotoxicity were decreased by supercritical fluid extract of complex herbal medicine. Conclusions : These results suggest that supercritical fluid extracts may have value as the potential antioxidant and antiaging medicinal plant.

• Bulletin of the Korean Chemical Society
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• v.26 no.2
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• pp.312-314
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• 2005

• Bulletin of the Korean Chemical Society
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• v.30 no.5
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• pp.1215-1217
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• 2009

• Journal of Industrial Technology
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• v.11
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• pp.3-16
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• 1991

The lattice-fluid theory are adopted for modeling the phese equilibria in supercritical fluids, In order to investigate effects of the nonrandom distribution of holes in mixtures on the phase equilibria, the equation of state and the chemical potential of the binary miture are formulated with taking into account nonrandomness of holes distributions in the fluid mixture. The relations of phase equilibria formulated in this work are tested through predictions of solubility of heavy solids in supercritical fluids and predictions of high pressure phase equilibria of binary mixtures. Results obtained exhibit that the lattice fluid model with assumptions of nonrandomness of hole distributions is successful in quantatively mideling the phase equilibria of mixtures of molecules of dissimilar sizes, specifically solids-supercritical fluid mixtures.