Supercritical fluid chromatography origin

Arpino, P.J., R Sadoun, and H. Virelizier. 1993. Reviews on recent trends in chromatography/ mass spectrometry coupling. Part IV. Reasons why supercritical fluid chromatography is not so easily coupled with mass spectrometry as originally assessed. Chromatographia 36 283-288. 

In the light of the aforesaid limitations of the application of gas chromatography or HPLC for the separation of compounds having limited volatility and thermal stability it is too obvious that there is need to use other alternatives for separating such compounds. Capillary supercritical fluid chromatography is such an alternative and although of comparatively recent origin, meets the said need adequately. 

Supercritical Fluid Chromatography. The origin of SFC with packed columns goes back over two decades (17-26). The recent interest in SFC has been due in large part to the limitations in both chromatographic efficiency and detection methods with HPLC. The introduction of fused silica capillary columns with nonextractable stationary phases for SFC (O and the potential compatibility with gas phase detection methods (13) has served to further increase the attention given these methods. 

Steady-State Solvatochromism. The majority of the reports on supercritical fluid solvation have used steady-state solvatochromic absorbance measurements (21-28). The original aim of these experiments was to determine the solvating power of supercritical fluids for chromatography and extraction (SFC and SFE) (26,28). To quantify solvent strength, researchers (21-28) adopted the Kamlet-Taft x solvent polarity scale (50-55). This scale best correlates solvatochromic effects on a- x and x- x electronic absorption transitions. 

Using a single substance as the mobile phase makes the instrumentation much easier than a multisubstance approach. In this case, the instrument could be a simple modification of HPLC equipment to also deal with a supercritical fluid, as used originally by Ishii. In this case, simply adjusting the mobile-phase pressure and temperature in order to be either in the SFC or LC mode can make the selection of the chromatographic mode (LC or SFC). This is the easiest way to perform unified chromatography but also the more limited one because it is difficult to find a... 

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