Extraction cells

Interfacial Contact Area and Approach to Equilibrium. Experimental extraction cells such as the original Lewis stirred cell (52) are often operated with a flat Hquid—Hquid interface the area of which can easily be measured. In the single-drop apparatus, a regular sequence of drops of known diameter is released through the continuous phase (42). These units are useful for the direct calculation of the mass flux N and hence the mass-transfer coefficient for a given system. 

Figure 6.4 Schematic diagram of an on-line SPE-SFE-GC system (from ref. 40) 1, carbon dioxide 2, high-pressure syringe pump 3, gas cliromatograph 4, tliree-poit valve 5, oven 6, extraction cell 7, waste 8, ten-port valve 9-11 conditioning and washing solvents 12, sample 13, niti Ogen.

Figure 6.5 Schematic diagram of a typical interface used for on-line SFE-GC coupling (from ref. 40) 1, extraction cell 2, restrictor 3, on-column injector 4, heater 5, oven 6, ayogenic module 7, column.

Fig. 123. Schematic structure of a mixer-settler extraction cell.

Dabora, S.L. Sheetz, M.P. (1988). The microtubule-dependent formation ofatubulovesicular network with characteristics of the ER from cultured cell extracts. Cell 54, 27-35. 

Although the improved extraction kinetics also increase the concentration of coextractives in the final extract, some degree of selectivity can be achieved by careful selection of the solvent or solvents used. Matrix co-extractives may be removed, or at least partially removed, by placing a suitable sorbent, such as alumina, at the exit of the extraction cell to remove lipid co-extractives. Excellent recoveries of both polar and nonpolar pesticides from a wide range of foodstuffs have been reported. Specific applications include organophosphorus and A-methylcarbamate pesticides. 

In the loop interface the fluid from the extraction cell passes continuously through an injection loop and into a collection vessel. Injection of a predetermined fraction of the extract onto a packed column is made by switching the loop so that it is in-line with the flow of fluid to the analytical... 

Use a cellulose thimble in the extraction cell (to prevent plugging). 

General applications The majority of reported analytical chromatographic applications of SFE to date have been concerned with the coupling of SFC (Section 7.1.1.4), using very small extraction cells, with... 

Blow, J. J., and Nurse, P. (1990). Acdc2-like protein is involved in the initiation of DNA replication in Xenopus egg extracts. Cell 62 855-862. 

Kumagai, A., and Dunphy, W. G. (1992). Regulation of the cdc25 protein during the cell cycle in Xenopus extracts. Cell 70 139-151. 

Belmont LD, Hyman AA, Sawin KE, Mitchison TJ (1990) Real-time visualization of cell cycle-dependent changes in microtubule dynamics in cytoplasmic extracts. Cell 62 579-589... 

Other claimed matter DBT for enrichment, biocatalyst preparation contacting process Enzymes contacting process Pure compounds as feedstock Membrane fragments and extracts Cell-free extract (envelope and its fragments + associated enzyme) reversible emulsion microemulsion reverse micelles Cell-free enzyme preparation microemulsified process RR and derivatives and other biocatalyst concepts + any known microorganism active for C—S bond cleavage... 

A 1-g sieved, air-dry soil sample is placed in an extraction cell with methanol as a modifier. The sample is extracted at a C02 flow rate of 1.5 mT/min with supercritical carbon dioxide for 15 minutes and analytes trapped in an octadecyl siloxane microextraction disk for subsequent analysis (adapted and condensed from Reference 9). 

The apparatus incorporates a fibre optic interface for the spectrofluorimetric measurement on the supercritical carbon dioxide emerging from the extraction cell of a supercritical fluid extractor, prior to depressurization from up to 350 bar. Recoveries of polyaromatic hydrocarbons are between 89 and 107%, and measurements can be carried on with a relative standard deviation of less than 5%. 

Breast adipose (endrin) Placement of adipose into extraction cell between layers of alumina followed by SFE with C02 and C02 modified with 5% dichloromethane analyte recovery into cyclohexane clean-up using neutral alumina GC/ECD 10 ppb 73 Djordjevic et al. 1994... 

Fig. 11 Extraction device consisting of A CO2 cylinder, B syringe pump, C oven, D extraction cell, E particle filter, F back-pressure regulator, G sampling tube...

To allow for solubility measurements by a dynamic procedure, equilibrium conditions have to be established in the extraction cell. If a sufficiently low flow rate is adjusted, the CO2 passing the extraction cell is loaded with an equilibrium substance amount in the steady state. 

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