21


if it is more efficient to extract all the material first, followed by separation or to use the extraction-injection technique. While further experiments are planned to elucidate this, it is quite probable that the best procedure will turn out to be application-dependent.


Acknowledgements


I wish to thank Neal Byrne of Lotus Separations LLC (Princeton, NJ) for running the LC-MS analyses.


References


Figure 11. Chromatogram of final product. CHIRALCEL OD-H 150 x 4.6 mm, 5% methanol in CO2 at 3 ml/ min, back pressure 100 bar. Injection 10µl. Detection UV at 230 nm. Oven temperature 40°C.


when the concentrations of the impurities in the injected material remain that in the original sample, the present method allows the concentration of the impurities and their elution within the first few injections. The higher concentrations also make it easier to detect and isolate minor components. Application of the technique to a natural product complicated the simple procedure by the kinetics of extraction from the organic matrix. Although some components were


rapidly extracted and eluted, other, more polar, compounds followed a much slower extraction regime which was probably controlled by lower solubility in the supercritical CO2


and diffusion from the


matrix. The major component of the cloves was isolated in good recovery and at very high purity. Thus, the method is clearly applicable to the rapid isolation of components of natural products by combining the extraction and separation into a single process. It is arguable


[1]. M Shaimi and G B Cox, Chromatography Today, November/December 2014, 7, 42.


[2] Farshad Yazdani, Morteza Mafi, Fathollah Farhadi, Kourosh Tabar-Heidar, Kioumars Aghapoor, Farshid Mohsenzadeh, and Hossein Reza Darabi Z. Naturforsch. 60b, (2005), 1197.


[3] Guan Wenqiang, Li Shufen, Yan Ruixiang, Tang Shaokun, Quan Can, Food Chemistry 101 (2007) 1558–1564


[4] Juliana M. Prado, Glaucia H.C. Prado, M. Angela A. Meireles, J. of Supercrit. Fluids, 56, (2011), 231.


[5] Helena Sovová, Chemical Engineering Science, 49, (1994), 409.


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