Supercritical-fluid chromatography applications

See alsa Distillation. Elemental Speciation Waters, Sediments, and Soils. Fuels Gaseous. Gas Chromatography Petrochemical Applications. Infrared Spectroscopy Near-Infrared Industrial Applications. Nuclear Magnetic Resonance Spectroscopy Overview. Sulfur. Supercritical Fluid Chromatography Applications. X-Ray Fluorescence and Emission Wavelength Dispersive X-Ray Fluorescence Energy Dispersive X-Ray Fluorescence. 

See also Capillary Electrochromatography. Capillary Electrophoresis Environmental Applications. Gas Chromatography Overview. Immunoassays Overview. Liquid Chromatography Overview. Mass Spectrometry Overview. Micellar Electrokinetic Chromatography. Sensors Overview. Spectrophotometry Ovenriew. Supercritical Fluid Chromatography Applications. Thin-Layer Chromatography Overview. 

Purity Determination Stabiiity Testing. Process Analysis Overview. Quality Assurance Quality Control Reference Materials Production of Reference Materials. Supercritical Fluid Chromatography Applications. 

Ashing Oxygen Flask Combustion. Supercritical Fluid Chromatography Applications. Thermal Analysis Ovenriew. X-Ray Fluorescence and Emission Wavelength Dispersive X-Ray Fluorescence Energy Dispersive X-Ray Fluorescence. 

Supercritical fluid chromatography has found many applications in the analysis of polymers, fossil fuels, waxes, drugs, and food products. Its application in the analysis of triglycerides is shown in Figure 12.38. 

Example of the application of supercritical fluid chromatography to the analysis of triglycerides. (Chromatogram courtesy of Alltech Associates, Inc. Deerfield, IL). 

A method which uses supercritical fluid/solid phase extraction/supercritical fluid chromatography (SE/SPE/SEC) has been developed for the analysis of trace constituents in complex matrices (67). By using this technique, extraction and clean-up are accomplished in one step using unmodified SC CO2. This step is monitored by a photodiode-array detector which allows fractionation. Eigure 10.14 shows a schematic representation of the SE/SPE/SEC set-up. This system allowed selective retention of the sample matrices while eluting and depositing the analytes of interest in the cryogenic trap. Application to the analysis of pesticides from lipid sample matrices have been reported. In this case, the lipids were completely separated from the pesticides. 

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. 

A number of analytical techniques such as FTIR spectroscopy,65-66 13C NMR,67,68 solid-state 13 C NMR,69 GPC or size exclusion chromatography (SEC),67-72 HPLC,73 mass spectrometric analysis,74 differential scanning calorimetry (DSC),67 75 76 and dynamic mechanical analysis (DMA)77 78 have been utilized to characterize resole syntheses and crosslinking reactions. Packed-column supercritical fluid chromatography with a negative-ion atmospheric pressure chemical ionization mass spectrometric detector has also been used to separate and characterize resoles resins.79 This section provides some examples of how these techniques are used in practical applications. 

Supercritical Fluid Chromatography with Packed Columns Techniques and Applications, edited by Klaus Anton... 

Supercritical fluid chromatography (SEC) was first reported in 1962, and applications of the technique rapidly increased following the introduction of commercially available instrumentation in the early 1980s due to the ability to determine thermally labile compounds using detection systems more commonly employed with GC. However, few applications of SEC have been published with regard to the determination of triazines. Recently, a chemiluminescence nitrogen detector was used with packed-column SEC and a methanol-modified CO2 mobile phase for the determination of atrazine, simazine, and propazine. Pressure and mobile phase gradients were used to demonstrate the efficacy of fhe fechnique. 

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]. 

K. Anton and C. Berger, Supercritical Fluid Chromatography with Packed Columns - Techniques and Applications, M. Dekker, New York, NY (1998). 

Figure 7.2 Molecular weight range applicable to chromatography and SFE. After Maeda and Hobo [39]. Reprinted from T. Maeda and T. Hobo, in Hyphenated. Techniques in Supercritical Fluid Chromatography and Extraction (K. Jinno, ed.), pp. 255-274, Copyright (1992), with permission from Elsevier...

In analytical chemistry there is an ever-increasing demand for rapid, sensitive, low-cost, and selective detection methods. When POCL has been employed as a detection method in combination with separation techniques, it has been shown to meet many of these requirements. Since 1977, when the first application dealing with detection of fluorophores was published [60], numerous articles have appeared in the literature [6-8], However, significant problems are still encountered with derivatization reactions, as outlined earlier. Consequently, improvements in the efficiency of labeling reactions will ultimately lead to significant improvements in the detection of these analytes by the POCL reaction. A promising trend is to apply this sensitive chemistry in other techniques, e.g., in supercritical fluid chromatography [186] and capillary electrophoresis [56-59], An alter-... 

Supercritical fluid chromatography employs supercritical fluid instead of gas or liquid to achieve separations. Supercritical fluids generally exist at conditions above atmospheric pressure and at an elevated temperature. As a fluid, the supercritical state generally exhibits properties that are intermediate to the properties of either a gas or a liqiud. Chapter 16 discusses various advantages of SFC over GC and HPLC and also provides some interesting applications. 

Bevan, C. D., Mellish, C. J. In Process-Scale Liquid Chromatography, Subramanian, G. (ed.) (VCH Verlagsgesellschaft, 1995) Chapter. 8. Scaling-up of supercritical fluid chromatography to large-scale applications. 

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