The uses of supercritical fluid chromatography

SFC is establishing itself as a complementary technique to both gas and liquid chromatography. Commercial equipment is now available for both packed and capillary SFC as well as for MS, FTIR and SFE coupling. Whilst capillary SFC to date still offers the most potential in terms of its separating power, several desirable instrument features have yet to be realised (quantitative and discrimination-free injection, column stability and adjustable flow control). 

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More recently, some studies have reported the use of supercritical fluid chromatography (SEC) [479,480], Coupling SEC with SEE, sample extraction, preconcentration, and quantification can be performed in a single step. The mobile phase, carbon dioxide, can be modified by adding different... 

The use of supercritical fluid chromatography for carotene separation has been examined and optimized, especially in regard to temperature, pressure, and organic modifiers in the supercritical fluid (71). With an RP column it was possible to resolve an a-carotene-cis isomer from an all-trans carotene as well as two cis isomers of /3-carotene from an all-trans /3-carotene. As with HPLC, only polymeric C,8 columns were able to resolve the cis isomers of a- and /3-carotene from the all-trans isomers. Supercritical fluid chromatography offers the advantage not only of an efficient separation but also of fast analysis. Indeed, the use of SFC with ODS-based columns for the analysis of carotenoid pigments affords a threefold reduction of analysis time compared to HPLC (72). The elution order of carotenoids and their cis isomers was found to be the same as in RP-HPLC. The selectivity of the system could further be increased by adding modifiers (e.g.,... 

Figure 7.13 Typical chromatogram for steroids (1) medroxyprogesterone acetate, 2.0 mg/ml (2) cortisone acetate, 2.0 mg/ml (3) methylpred-nisolone acetate, 2.0 mg/ml (4) isoflupredone acetate, 2.0 mg/ml (5) hydrocortisone, 1.6 mg/ml. [Reprinted from Ref. 13, J. Pharm. Biomed. Anal. 8, Loran and Cromie, An Evaluation of the Use of Supercritical Fluid Chromatography with Light Scattering Detection for the Analysis of Steroids (1990) with kind permission from Elsevier Science Ltd, The Boulevard, Langford Lane, UK.]...

Steuer et al. demonstrated the use of supercritical fluid chromatography in the separation of enantiomers of 1,2 amino alcohols, namely pindolol, metoprolol, oxprenolol, propranolol, and DPT 201-106 using ionpairing modifiers [21]. The mobile phase consisted of carbon dioxide mixed with acetonitrile containing triethylamine as a counterion and /V-benzo-xycarbonylglycyl-L-proline as a chiral counterion. They found that the ca-... 

J.S. Loran and K.D. Cromie, An evaluation of the use of supercritical fluid chromatography with light scattering detection for the analysis of steroids, J. Pharm. Biomed. Anal., 8 607 (1990). 

The use of supercritical-fluid chromatography (SEC) coupled to ICP-MS was applied for the separation and detection of TEL and tributyl lead acetate, although the apparent instability of tributyl-lead acetate under SF conditions and the presence of an additional peak when the mixture is injected does not favor its determination by SFC-ICP-MS. The use of SFC-ICP-MS for the quantification of TEL in SRM NIST 2715 Lead in Reference Fuel gave results in excellent agreement with the certified values. 

Van Anda, J. The use of supercritical fluid chromatography (SFC) for chiral pharmaceutical analytical and preparative separations. Am. Pharm. Rev. 12 48-53, 2009. 

Further applications of M IPs for speciation include the use of supercritical-fluid chromatography for the determination of P, Cl, N, Si, Fe, and Zn species as car lubricant additives [531]. Hyphenation of packed-column supercritical fluid chromatography (SFC) to microwave-induced plasma optical emission spectrometry (MIP-OES) by flow-splitting via a restrictor to enable multi-detection, including UV or flame-ionization detection, has also been described. 

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... 

In terms of chromatography, the first individual credited with the use of supercritical fluids as the mobile phase is Ernst Klesper when in 1962 he reported on the separation of metal porphyrins using dense-gas chromatography (GC) or SFC [3]. But it was not until the 1980s that the analytical community took hold of the abilities and advantages of the technique with the advent of several commercial instrumentation ventures. 

The advantages of supercritical fluid chromatography for polymer separations have been illustrated in the literature for many years. A recent example is the separation of long-chain polyprenols using SFC with matrix-assisted laser-desorption ionization TOF mass spectrometry [10]. The generic name for 1,4-polyprenyl alcohols is polyprenol these compounds generally have smaller polymerization chains of less... 

The prerequisites for the use of gas chromatography as an analytical tool in enantiomer analysis, i.e., quantitative resolvability, substrate volatility and thermal stability, tend to restrict its general use. The development of supercritical fluid chromatography (SFC) for enantiomer... 

Supercritical fluid extraction, offers also some desirable advantages including processing at low temperature, recovery of a solvent-free extract, and rapid extraction. However, very limited studies have been published on the use of supercritical fluids for the isolation of corticosteroids from biological samples. A combination of supercritical fluid extraction and liquid chromatography has been employed for the detection of dexamethasone residues in bovine tissues (448). 

The use of supercritical fluids as mobile phases in chromatography can offer several advantages because their properties are between those of liquids and those of gases. In particular, the viscosity of a supercritical fluid is almost that of a gas (50 times lower than that of a solvent) while its solvation properties (governed by the distribution coefficients K) are similar to those of a nonpolar solvent such as benzene. 

A. Medvedovid, A. Kot, F. David, and P. Sandra, The use of supercritical fluids in environmental analysis, in Supercritical Fluid Chromatography with Packed Columns (K. Anton and C. Berger, eds.), Marcel Dekker, Inc., New York, 1998, pp. 369 - 401. 

The term supercritical fluid is used to describe any substance above its critical temperature and pressure. The discovery of the supercritical phase is attributed to Baron Cagniard de la Tour in 1822 [3], He observed that the boundary between a gas and a liquid disappeared for certain substances when the temperature was increased in a sealed glass container. While some further work was carried out on supercritical fluids, the subject remained essentially dormant until 1964 when a patent was filed for using supercritical carbon dioxide to decaffeinate coffee. Subsequent major developments by food manufacturers have led to the commercialization of this approach in coffee production. The use of supercritical fluids in the laboratory was initially focused on their use in chromatography, particularly capillary supercritical fluid chromatography (SFC). However, it was not until the mid-1980s that the use of SFE for extraction was commercialized. 

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