SUPERCRITICAL FLUID EXTRACTION AND CHROMATOGRAPHY

Analytical Supercritical Fluid Extraction and Chromatography Supercritical fluids, especially CO9, are used widely to extrac t a wide variety of solid and hquid matrices to obtain samples for analysis. Benefits compared with conventional Soxhlet extraction include minimization of solvent waste, faster extraction, tunabihty of solvent strength, and simple solvent removal with minimal solvent contamination in the sample. Compared with high-performance liquid chromatography, the number of theoretical stages is higher in... 

B. Wenclawiak (Ed.), Analysis with Supercritical Fluids Extraction and Chromatography, Springer-Verlag, Berlin (1992). 

Henry, M.C. andYonker, C.R., Supercritical fluid chromatography, pressurized hquid extraction, and supercritical fluid extraction. Anal. Chem., 78, 3909, 2006. Wenclawiak, B., Ed., Analysis with Supercritical Fluids Extraction and Chromatography, Springer Verlag, Berlin, 1992. 

B.A. Charpentier and M.R. Sevenants (eds), Supercritical Fluid Extraction and Chromatography Techniques and Applications, ACS Symposium Series 366, American Chemical Society, Washington, DC (1988). 

M.S. Verrall (ed.), Supercritical Fluid Extraction and Chromatography, John Wiley Sons, Ltd, Chichester (1996). 

Ashraf-Khorassani M, Taylor LT, Zimmerman P. Nitrous oxide versus carbon dioxide for supercritical fluid extraction and chromatography of amines. Anal. Chem. 1990 62 1177-1180. 

C. Turner, J.W. King and L. Mathiasson, Supercritical fluid extraction and chromatography for fat-soluble vitamin analysis. J. ChromatogrA 936 (2001) 215-237. 

B. WENCLAWIAK, "Analysis with Supercritical Fluids Extraction and Chromatography", Springer-Verlag, Heildeberg, 1992. 

The single largest use of ammonia is its direct apphcation as fertdizer, and in the manufacture of ammonium fertilizers that have increased world food production dramatically. Such ammonia-based fertilizers are now the primary source of nitrogen in farm soils. Ammonia also is used in the manufacture of nitric acid, synthetic fibers, plastics, explosives and miscellaneous ammonium salts. Liquid ammonia is used as a solvent for many inorganic reactions in non-aqueous phase. Other apphcations include synthesis of amines and imines as a fluid for supercritical fluid extraction and chromatography and as a reference standard in i N-NMR. 

Lira, C.T. Supercritical Fluid Extraction and Chromatography, ACS Symposium Series No. 366, "Physical Chemistry of Supercritical Fluids" 1988, pp. 1-25. 

Lin, Y. Smart, N.G. Wai, C.M. Supercritical fluid extraction and chromatography of metal chelates and organometallic compounds, Trends Anal. Chem. 14 (1995) 123-133. 

Oudsema, J.W. and Poole, C.F. (1992) On-line supercritical fluid extraction and chromatography of organotins with packed microbore columns and formic acid modified carbon dioxide. Fresenius J. Anal. Chem., 344, 426-434. 

Some Useful Fluids for Supercritical Fluid Extraction and Chromatography P-p-T Table for Carbon Dioxide... 

SOME USEFUL FLUIDS FOR SUPERCRITICAL FLUID EXTRACTION AND CHROMATOGRAPHY... 

The following table provides a numerical listing of the P-p-T surface for carbon dioxide in the region of interest for supercritical fluid extraction and chromatography. These data were calculated using an empirical equation of state (the Schmidt-Wagner equation),12 the parameters of which were determined from a fit of experimental P-V-T (pressure-volume-temperature) measurements.3 8 Note that the pressures are tabulated in bars for convenience. The appropriate SI unit of pressure is the megapascal (1 bar = 0.1 MPa). 

The following table provides the solubility parameters, 8, for the most common fluids and modifiers used in supercritical fluid extraction and chromatography. The data presented in the first table are for carrier or solvent supercritical fluids at a reduced temperature, T of 1.02 and a reduced pressure, P of 2. These values were calculated with the equation of Lee and Kesler.1 2 The data presented in the second table are for liquid solvents that are potential modifiers.3... 

In this table, we provide solubility parameters for some liquid solvents that can be used as modifiers in supercritical fluid extraction and chromatography. The solubility parameters (in MPa1/2) were obtained from reference 3, and those in cal1/2cm 3/2 were obtained by application of Equation 4.1 for consistency. It should be noted that other tabulations exist in which these values are slightly different, since they were calculated from different measured data or models. Therefore, the reader is cautioned that these numbers are for trend analysis and separation design only. For other applications of cohesive parameter calculations, it may be more advisable to consult a specific compilation. This table should be used along with the table on modifier decomposition, since many of these liquids show chemical instability, especially in contact with active surfaces. 

I.J. Koski, B.A. Jansson, K.E. Markides and M.K. Lee, Analysis of prostaglandins in aqueous solution by supercritical fluid extraction and chromatography, J. Pharm. Biomed. Anal., 9 281 (1991). 

M. Masuda, S. Koike, M. Handa, K. Sagara, and T. Mizutani, Application of supercritical fluid extraction and chromatography to assay fat-soluble vitamins in hydrophobic ointment, Anal. Sci., 9 29 (1993). 

Supercritical Fluid Extraction and Chromatography of Nonpolar Nonvolatile Coal-Derived Products... 

Sanagi, M.M., Ahmad, U.K. and Smith, R.M. (1993) Application of supercritical fluid extraction and chromatography to the analysis of tumeric. Journal of Chromatographic Science 31, 20-25. 

---