Extraction Vessel and Oven

From the pump the fluid travels to a heated zone, where it becomes supercritical, and then to an extraction vessel where the sample is contained. The extraction vessel and connecting tubes are housed in an oven, so the temperature is kept constant during extraction. Density determines the extraction efficiency and is dependent on pressure and temperature in the supercritical zone. It is essential to maintain a rigorous control of both parameters during the extraction. 

FIGURE 2.22 Liquid matrix extraction cell. (Reprinted from Heldrich, J. L. and Taylor, L. T., Anal. Chem., 61, 1986-1988, 1989. With permission from American Chemical Society.) 

The extraction vessel, usually made of stainless steel, is the compartment where the sample is placed in order to be extracted by the SF, and its temperature must remain greater than the critical temperature. The extraction cell must have the following characteristics  

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