Supercritical fluid chromatography characterized

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. 

Beside the use of MIPs in conventional HPLC, Mi-polymers may also be established in supercritical fluid chromatography, which is characterized by faster equilibration times combined with the use of the environmental friendly C02 as mobile phase. Although preliminary results show relatively broad peaks, chiral separation could be performed based on polymers imprinted with an enantiomer. However, the long-term stability of the photochemically generated polymers seems to be a problem [89]. 

Chemists in its Methods of Analysis, 8th ed. Methods have also been developed for DON by TLC (93) and for several trichothecenes both by immunoassay (94,95) and by supercritical fluid chromatography (96). In comparison with LC, supercritical fluid chromatography is characterized by sharper peaks and faster analysis times, similar to those obtained by capillary GC. 

Clifford, A.A. Chalmers, J.M. Cook, B.W. Polymer additive characterization by capillary supercritical fluid chromatography/Eourier transform infrared microspectrometry. Anal. Chem. 1988, 60, 427-433. 

M. W. Raynor, K. D. Bartle, I. L. Davies, A. Williams, A. A. Clifford, J. M. Chalmers, and B. W. Cook, Polymer additive characterization by capillary supercritical fluid chromatography/Fourier transform infrared microspectrometry, A aZ. Chem. 60 427-433 (1988). 

Characterization in the solid-state and compendial methods has been discussed already. Quantitative tests to characterize drug substance and drug product composition require that significant consideration be given to method development. Methods such as thin layer chromatography, gas chromatography, HPLC, supercritical fluid chromatography, and capillary electrophoresis... 

A number of researchers have developed techniques to determine partial molar volume. Eckert and coworkers (Eckert et al., 1986) provide a very good description of the method for obtaining partial molar volumes. They facilitated this difficult measurement by using a vibrating-tube densitometer (Mettler-Paar DMA 512). The major uncertainties with this technique are associated with the temperature control, which becomes crucial if experiments are performed at infinite dilution near the solvent s critical point. Shim and Johnston (1991) also note that it is possible to determine partial molar volume information using supercritical fluid chromatography if the mobile and stationary phases can be thermodynamically characterized. 

Infrared spectroscopy is probably the most widespread analytical spectroscopic technique for identification and characterization of organic compounds. Because of this identification capability infrared spectroscopy is desirable as a detection technique for chromatographic separations. With the advent of Fourier transform infrared spectroscopy/ the speed and sensitivity of infrared detection is greatly enhanced making such applications feasible. FT-IR detection has been widely accepted as a detector for gas chromatography (GC/FT-IR) (1) and has been applied with limited success to liquid chromatography (LC/FT-IR) (2)/ and more recently to supercritical fluid chromatography (SFC/FT-IR) (3). The recent review articles cited here provide excellent introduction and references to current state-of-the-art in these areas. 

Sakurada, N., Fukuo, T., Arakawa, R., Ute, K., and Hatada, K., Characterization of Poly(methyl methacrylate) by Matrix-assisted Laser Desorption Ionization Mass Spectrometry. A Comparison with Supercritical Fluid Chromatography and Gel Permeation Chromatography, Rapid Comm, Mass Spectrom., 12, 1895, 1998. 

Characterization of lipids by supercritical fluid chromatography and supercritical fluid extraction... 

Comparison of supercritical fluid chromatography with other separation techniques for lipid characterization... 

Andersson, P. E., Demirbuker, M. and Blomberg, L. G. (1993) Characterization of fuels by multi-dimensional supercritical fluid chromatography and supercritical fluid chromatography-mass spectrometry. J. Chromatogr., 641, 347-55. 

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