Pressure drop during extraction

Compared with conventional particle-packed SPE cartridges, FIT-SPE provides an increased surface area for the extraction medium and a reduced pressure drop during extraction and desorption. Also, the undesirable plugging effect from insoluble materials in real samples can be very much diminished. Utilization of FIT-SPE has been discussed in a few review articles concerning the on-line coupling of miniaturized SPE to microcolumn liquid-phase separation techniques.24,25... 

The pressure drop in the SCF during transfer of the extract to the chromatograph should be as low as possible. 

In many cases solids progressively soften during extraction. This is particularly true when solids tend to decompose because of solubilization reactions. Flow pressure drop can strongly compact such solids. In such cases, compression permeability mensurements should be used to determine the flow resistance characteristics of the solid bed. If flow-induced compaction is excessive it may be necessary to reduce bed depth or use a larger than normal flow cross-sectional area. 

The requirements for correct operation of SFE-SFC technique are (i) the extraction chamber volume must be appropriate for the sample size in SFC (ii) the SF pressure drop (mobile phase) during the extract transfer to the chromatograph must be minimum, and (iii) the chromatograph must be pressurized and equilibrated to the required pressure before the injection of extracts. 

Fonnation pressure dropped to 40 kg/cm. For each 1,000,000 tons of oil produced during Period I, about 7 kg/cm equivalent of formadon energy was expanded. In this manner, in the course of nearly two years time nearly 4,000,000 tons of oil were extracted, that is 45% of all the oil recovered from the field during its entire period of production. During the entire Period 1, the reservoir drive was provided by gas dissolved in oil and by the elasticity forces of the crude. 

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