Carbon dioxide extract chromatogram

Volatile ginger oil obtained from steam distillation has been the subject of many research studies (5-12). However, the thermal degradative effects of steam distillation upon volatile and nonvolatile components of ginger were seldom discussed. Recently, Moyler (1) compared the advantages of liquid carbon dioxide extraction over conventional methods such as solvent extraction or steam distillation by showing reconstructed GC chromatograms which clearly displayed the differences. However,quantitative results showing the differences were not mentioned. 

Figure 8. Gas Chromatogram - Carbon Dioxide Extract (5000 psi) of Ginger.

Approximately 11% by weight of the parent material could be extracted using carbon dioxide at 60°C up to a pressure of 648 bar. A summary of a carbon dioxide extraction of GAP L-11391 is given in table 9.23. Reverse phase HPLC chromatograms which demonstrate the removal of the low molecular weight species from the parent material are given in figure 9.32. 

Figure 9.32 HPLC chromatograms of L-11391 fractions from carbon dioxide extraction.

Figure 8. Capillary GC chromatograms obtained from supercritical carbon dioxide extraction at two different pressures of orange peel.

Figure 9. Capillary GC chromatogram obtained from the supercritical carbon dioxide extraction of XAD-2 resin.

In normal high pressure liquid chromatography, typical sample volumes are 20-200 p.L this can become as little as 1 nL in capillary HPLC. Pretreatment of the sample may be necessary in order to protect the stationary phase in the column from deactivation. By employing supercritical fluids such as carbon dioxide, pretreatment can be bypassed in many instances so that whole samples from industrial and environmental matrices can be introduced directly into the column. This is due to the fact that the fluid acts as both extraction solvent and mobile phase. Post-column electrochemistry has been demonstrated. For example, fast-scan cyclic voltammo-grams have been recorded as a function of time after injection of microgram samples of ferrocene and other compounds in dichloromethane solvent and which are eluted with carbon dioxide at pressures of the order of 100 atm and temperatures of 50°C the chromatogram is constructed as a plot of peak current vs. time [18]. 

Fig. 1 Chromatogram of PAHs, herbicides, and phenols obtained by supercritical carbon dioxide modified with methanol. [Reprinted from L. Toribio, M. J. del Nozal, J. L. Bernal, J. J. Jimenez, and M. L. Serna, Packed-column supercritical fluid chromatography coupled with solid-phase extraction for the determination of organic microcontaminants in water,...

Figure 9.14 Gel permeation chromatograms of PMMA-g-PDMS copolymer before and after extraction with supercritical carbon dioxide. GPC trace of extract (PDMS macromonomer) is shown, too (Hell-stern, 1989).

Figure 9.56 HPLC chromatogram of the purified fraction obtained by extracting commercially available BisGMA with supercritical carbon dioxide (1) 1-chloro-isopropanol methacrylate (2) BisGMA and (3) diglycidyl ether of bisphenol-A.

Figure 3. Capillary GC chromatograms of the supercritical carbon dioxide (bottom) and methanol modified carbon dioxide (top) extracts of a hazardous waste sample.

Figure 2.5 Supercritical fluid chromatogram, with use of a miniaturized evaporative lightscattering detector, of an extract obtained from oat bran. Column 100 nun x 0.9 mm, packed with LiChrosorb Diol, 5 pm. Conditions temperature 22°C pressure 300 atm. Mobile phase carbon dioxide modified with 19 mol% methanol. Restrictor 45 mm x 9 pm at 90°C. Peaks TG = triacylglycerols MGDG = monogalactosyldiacylglycerols PC = phosphatidylcholines DGDG = digalactosyldiacylglycerols.

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