Dual-stage extraction

Figure 13.1 Schematic of TOF mass spectrometers having sources with (a) single-stage ion extraction, (b) dual-stage extraction and (c) dual-stage extraction to a second-order focus plane.

FIGURE 2.5 Comparison of single-stage and dual-stage extraction. 

Dual-stage Extraction and Space Focusing. As we noted above, the location of the space-focus plane is independent of mass, while ions of different mass are focused at the space-focus plane at different times. However, mass dispersion at this short distance from the source is usually not sufficient to allow the location of a detector at this point. Thus, one solution is to move the location of the space-focus plane to... 

In dual-stage extraction instruments, the time in the source rcgioif... 

When designing a time-of-flight instrument with dual-stage extraction, one first chooses values for the drift length (D) and the lengths of the source ) and extraction (si) regions. These then uniquely determine the ratio Ei/Eq. If one then chooses a... 

Schlag ct have obtained second-order solutions for the flight times of spatially distributed ions accelerated in a dual-stage extraction system. Using the notation shown in Figure 2.6, their relationship between the distances and. xijp is ... 

Dual solvent fractional extraction (Fig. 7b) makes use of the selectivity of two solvents (A and B) with respect to consolute components C and D, as defined in equation 7. The two solvents enter the extractor at opposite ends of the cascade and the two consolute components enter at some point within the cascade. Solvent recovery is usually an important feature of dual solvent fractional extraction and provision may also be made for reflux of part of the product streams containing C or D. Simplified graphical and analytical procedures for calculation of stages for dual solvent extraction are available (5) for the cases where is constant and the two solvents A and B are not significantly miscible. In general, the accurate calculation of stages is time-consuming (28) but a computer technique has been developed (56). 

Figure 13.8 Schematic of (a) space focusing on a dual-stage source and (b) space-velocity correlated focusing from a dual-stage source after delayed extraction.

Extract with DCM. Concentrated and loaded onto a dual-stage carbon sorbent trap. SPED Extract with DCM or solid-phase extraction on two adsorbents (C8 and activated carbon), and elute with ethanol Extract with DCM. Wastewater (CLLE)... 

Figure 2.5 Possible technological solutions to bioprocess problems a) Fed-batch culture b) Continuous product removal (eg dialysis, vacuum fermentation, solvent extraction, ion exchange etc) c) Two-phase system combined with extractive fermentation (liquid-impelled loop reactor) d) Continuous culture, internal multi-stage reactor e) Continuous culture, dual-stream multi-stage reactor f) Continuous culture with biomass feedback (cell recycling). (See text for further details).

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