Recent Developments in SFC and SFE

The flame ionisation detector (FID) has been used in analytical SFC and could be used in preparative SFC by by-passing a very small fraction of the mobile phase flow through to the detector. Obviously the FID could not operate in a largely carbon dioxide atmosphere and would respond to many modifiers. The photoionisation detector (PID) has been used in analytical SFC but is better suited to highly sensitive detection of specific types of compound. 

The refractive index (RI) detector as used for analytical and preparative HPLC does suffer from being quite sensitive to the refractive index changes which take place in the superciritical fluid as its pressure and hence density fluctuate. It often takes some time for such detectors to settle down in chromatographic systems. 

The diode array UV detector (DAD) has been employed for preparative SFC [13] and this has the advantage that the eluting materials may be partially characterised by acquisition of their UV absorption spectrum directly in the flowing stream. The light scattering detector (LSD) is a recent detector development that has found useful application in SFC. 

Recent developments in the preparative supercritical fluid chromatography and extraction area include the following commercially available instruments and iimova-tions. Suprex have introduced the Prepmaster and Accutrap, two new products for automated quantitative sample preparation. The Prepmaster is a dedicated supercritical fluid ctraction system designed for analytical and semi-preparative extractions. It can be used on-line, directly interfaced to a gas chromatograph or SFC or off-line with the Accutrap cryogenic collection module. The Prepmaster can accommodate extraction vessels with capacities from 0.5 to 8 mL. 

8 Scaling-up of Supercritical Fluid Chromatography to Large-Scale Applications 

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