Design of SFC Apparatus

The flow of the SCF under pressure is maintained by long-stroke piston pumps, reciprocating piston pumps, or membrane pumps which deliver the mobile phase in liquefied form. The fluid is then heated to supercritical conditions before entering the column. Pressure and flow rate must be kept as constant as possible in order to maintain constant conditions for separation and to achieve a stable baseline in the chromatogram. Oscillating pumps can therefore have three heads, which deliver at different times, or a pulsation dampener in order to minimize pulsation. [Pg.105]

In preparative and more so in productive SFC, the quantity of the mobile phase is not small and it must be recycled. To avoid backmixing, the recycled mobile phase must be totally free from any dissolved substances. Concentrations of the dissolved substances are low. In most cases they will be of the order of 0.1 % or even 0.01 %. Then, separation methods for the dissolved substances from the mobile phase become important. [Pg.105]

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