SFC—Supercritical Fluid Chromatography

Supercritical fluid chromatography (SFC) uses sc-gases as mobile phase [29-32]. In contrast to classical HPLC, the recycling of the solvent is much easier. The sep- 

A procedure for the isolation of vitamin D3 from a mixture of steroids, for example dehydrocholesterol, lumisterol, and tachysterol using SFC (SCCO2 and an optional modifier) was described by Johannsen [34] (Fig. 13.5). 

The advantage of this new procedure is that the wrong isomers are recycled. This resulted in a more efficient process and a minimum of waste. A block diagram is shown in Fig. 13.6. The experiments are carried out using SCCO2 (and modifier) at 100 to 200 bar, the column has the dimensions of 400 x 30 mm, at a 

Supercritical fluids have been used as mobile phases in liquid chromatography for about 30 years, and this modality is known as supercritical fluid chromatography (SFC). When both the temperature and the pressure of the system exceed the critical values - that is, the critical temperature T ) and the critical pressure (Pc)-the fluid is considered to be critical in nature. These fluids have a mixture of the properties of liquids and gases. Supercritical fluids (SFs) are highly compressible like gases, and their density and viscosity can be maintained by changing the pressure and temperature conditions, as in the case of liquids. In chromatographic systems. 

Chiral compounds of agricultural interest were used to probe the advantages or limitations of SFC relative to LC for enantiomeric separations. Column equilibrium and other parameter optimization were generally accomplished more rapidly in SFC than in LC. Although improved resolution was often observed in SFC, analysis times were not always lower in SFC than in LC yet, in some instances, SFC provided separation capabilities that were not readily accessible in LC. 

Supercritical fluid chromatography is the name for all chromatographic methods in which the mobile phase is supercritical under the conditions of analysis and the solvating properties of the fluid have a measurable effect on the separation. SFC has some advantages over GC and HPLC it extends the molecular weight range of GC, thermally labile compounds can be separated at lower temperatures, compounds without chromophores can be sensitively detected, and the use of open-tubular and packed columns is feasible. SFC can be employed in both the analysis of natural pigments and synthetic dyes, however it has not been frequently applied in up-to-date analytical practice. 

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Supercritical Fluid Chromatography. Supercritical fluid chromatography (sfc) combines the advantages of gc and hplc in that it allows the use of gc-type detectors when supercritical fluids are used instead of the solvents normally used in hplc. Carbon dioxide, -petane, and ammonia are common supercritical fluids (qv). For example, carbon dioxide (qv) employed at 7.38 MPa (72.9 atm) and 31.3°C has a density of 448 g/mL. 

Other multidimensional systems, such as supercritical fluid chromatography (SFC-GC or LC-SFC), will not be described here because, although some applications to environmental analysis have been described (4, 7-9), they have not been very widely used in this field. 

Supercritical fluid chromatography (SFC) refers to the use of mobile phases at temperatures and pressures above the critical point (supercritical) or just below (sub-critical). SFC shows several features that can be advantageous for its application to large-scale separations [132-135]. One of the most interesting properties of this technique is the low viscosity of the solvents used that, combined with high diffusion coefficients for solutes, leads to a higher efficiency and a shorter analysis time than in HPLC. 

Supercritical fluid chromatography (SFC) provides a means of minimizing the limitations of CSPs developed for FC while retaining the impressive chiral selectivity that has been achieved through the evolution of CSPs during the past two decades [6, 7]. The use of supercritical fluids as eluents for chromatographic separations was... 

Principles and Characteristics Klesper et al. [14] have introduced supercritical fluid chromatography (SFC). The oil industry has been a major force in the development of many aspects of the application of supercritical fluids. Much of the pioneering development of SFC was carried out by Sie and Rijnders [231,232], who also coined the term supercritical fluid chromatography [233]. 

Another concentration technique similar in principle to supercritical fluid chromatography, SFC (p. 

In supercritical fluid chromatography (SFC) the mobile phase is a supercritical fluid, such as carbon dioxide [15]. A supercritical fluid can be created either by heating a gas above its critical temperature or compressing a liquid above its critical pressure. Generally, an SFC system typically has chromatographic equipment similar to a HPLC, but uses GC columns. Both GC and LC detectors are used, thus allowing analysis of samples that cannot be vaporized for analysis by GC, yet cannot be detected with the usual LC detectors, to be both separated and detected using SFC. SFC is also in other... 

Supercritical fluid chromatography (SFC) can, in principle, be a very suitable means of analysis due to the high solubility of non-ionics in CO2... 

Non-ionic surfactants of a commercial washing powder were separated by supercritical fluid chromatography (SFC) and determined by APCI-MS. The constituents were first extracted by supercritical fluid extraction (SFE) using C02 with or without methanol as a modifier. Variations of the conditions resulted in a selective extraction of the analytes, which could be determined without further purification. Six groups of surfactants were observed, four of which are alkyl-polyethoxylates. The presence of APEO could be excluded by identification recording SFC-FTIR (Fourier transform infrared) spectra [31]. 

A. Kamangerpour, M. Ashraf-Khorassani, L.T. Taylor, H.M. McNair and L. Charida, Supercritical fluid chromatography (SFC) of polyphenolic compounds in grape seed extract. Chromatographia 55 (2002) 417 -21. 

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