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Showing 1 to 20 of 121 for “"Supercritical fluid"”.
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Capillary supercritical fluid chromatography
… of a gas chromatograph for capillary supercritical fluid was demonstrated. The resulting instrument was used to characterize the performance of capillary columns manufactured specifically for SFC applications. The columns were tested for inertness, efficiency, and immobilization before …
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Supercritical fluid chromatography - mass spectrometry
… quality separations other techniques, such as supercritical fluid<br/>chromatography (SFC), are now being considered. The key advantage of SFC is minimal<br/>solvent waste, which is particularly important in preparative SFC, leading to fast sample<br/>recovery. Hence it is important to explore …
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Adiabatic Packed Column Supercritical Fluid Chromatography
A well-known problem in supercritical fluid chromatography is the drastic decrease in chromatographic performance at temperatures above 40 C and outlet pressures below 120 bar. This phenomenon has been attributed to isenthalpic expansion and cooling of the mobile phase and poor heat transport under …
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Thermoacoustic Oscillations in Supercritical Fluid Flows
Pressure oscillations in supercritical Jet-A fuel flowing through four parallel, heated tubes connected to common manifolds have been observed in this study. Tests were performed with fuel inlet temperatures ranging from 70F to 700F, and fuel pressures ranging from 360-700 psi. Total fuel flow rate …
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Supercritical Fluid Chromatography of Ionic Compounds
… the elution of ionic analytes via packed column supercritical fluid chromatography (SFC). Firstly, we focused on the elution of sodium arylsulfonate analytes by using various ionic additives, such as lithium acetate, ammonium acetate, tetramethylammonium acetate, tetrabutylammonium acetate, and …
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Quantitative Analysis of Additives in Low Density Polyethylene Using On-line Supercritical Fluid Extraction /Supercritical Fluid Chromatography
… lower than 90%. In recent years, analysis with supercritical fluids (SFs) has emerged as an alternative analytical technique because SFs afford higher diffusivity and lower viscosity. In this research, an on-line Supercritical Fluid Extraction (SFE)/Supercritical Fluid Chromatography (SFC) …
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Supercritical fluid extraction of non-traditional matrices
Supercritical extraction (SFE) has most often been linked to the use of modified or unmodified CO₂ for the recovery of relatively non-polar analytes from solid matrices. The objective of this research was to expand current supercritical fluid (SF) techniques to the recovery of analytes from …
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Liquid collection efficiencies after supercritical fluid extraction
The design of any supercritical fluid extraction (SFE) experiment should break down into two parts: 1) removal of the analytes of interest from the bulk matrix and 2) deposition of those analytes in a user friendly manner for further studies (spectroscopy or chromatography). While great attention …
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Aspects of the microwave induced plasma as an element selective detector for supercritical fluid chromatography and supercritical fluid extraction
The introduction of supercritical CO₂ at packed column supercritical fluid chromatography (SFC) flow rates is shown to significantly affect the excitation characteristics of a helium microwave induced plasma (He MIP). In this work, the influence of CO₂ on specific atomic and ionic transitions of …
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Experimental and Theoretical Studies of Supercritical Fluid Behavior
… amino acids, tryptamine and histamine, in supercritical ammonia (supercritical in pressure only) at 50(DEGREES)C. Solubilities are obtained for the pure solids and mixtures of the solids in 1:1 mole ratio. The solubilities of the mixed solids are determined using thin-layer chromatography. …
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Specific intermolecular interactions for tailoring supercritical fluid solutions
Investigations of supercritical fluid solutions containing cosolvents are described; in addition, recommendations for future work to improve the understanding of these solutions are made.
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Investigation of Liquid Trapping Following Supercritical Fluid Extraction
Supercritical fluid extraction (SFE) is an alternative to traditional extractions with organic solvents. SFE consists of removing the analyte(s) from the matrix, solubilizing them, moving the analyte(s) into the bulk fluid, and sweeping the fluid containing the analyte(s) out of the extraction …
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Analysis of polar compounds by supercritical fluid chromatography
The analysis of polar compounds has been studied by SFC using 100% CO₂ or methanol modified CO₂ as the mobile phase. Both microbore packed and capillary columns are employed to separate the mixtures of steroids and agricultural compounds of various chemical classes such as amides, sulfonamides and …
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Novel Switchable Stationary Phase Methods For Supercritical Fluid Chromatography
In the first part of this thesis, a supercritical fluid chromatography-flame ionization detection (SFC-FID) system employing a modified water stationary phase was investigated for the analysis of organic bases. The method uses a stainless steel capillary column coated with water containing NH4OH, …
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Intermolecular interactions in supercritical fluid solutions from fluorescence spectroscopy
Much of the unusual behavior in supercritical fluids (SCF's), including enhanced solubilities, synergistic effects of mixed solutes, and entrainer effects, may be explained by a region around the solute that has a higher density than the bulk. We present a new technique to investigae SCF's using …
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Supercritical Fluid Chromatography with Chemiluminescent Nitrogen and Sulfur Detection
The need for sensitive and selective detectors in supercritical fluid chromatography (SFC) is particularly evident since SFC can be used to analyze classes of compounds that are not readily amenable to either gas chromatography (GC) or liquid chromatography (LC). These compounds include species …
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Applications of modifiers in supercritical fluid extraction and chromatography
The use of modifiers in supercritical fluid chromatography and extraction has become quite common due to the inability of pure carbon dioxide alone to solvate many of the compounds of interest. The effects of modifiers in supercritical fluid chromatography have been more thoroughly studied than the …
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A method for direct coupling of supercritical fluid extraction and supercritical fluid chromatography with application to the analysis of nonvolatile coal derived products
In recent years supercritical fluid chromatography has gained attention as an alternative technique to high performance liquid chromatography for the analyses of nonvolatile or thermally labile compounds, whose analysis with gas chromatography is impossible. The work presented here demonstrates a …
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