Sorption column systems

Plantz et al.[20] proposed an on-line sorption column system to eliminate interferences from alkali and alkaline earth elements and anions in the ICP-MS determination of various trace metals in sea water samples. The bis(carboxymethyl)- dithiocarbamate reagent was used to complex V, Cr, Ni, Co. Cu, Mo. Pt, Hg, and Bi. Under acidic conditions, the complexes were sorbed on a column packed with XAD-4, while the interferents passed freely through. The retained analytes were then eluted with 0.1 M NH4OH into the ICP-MS. The detection limits were in the range 8-80 ng 1 using a 0.5 ml sample loop. The precision was in the range 3 to 5 % r.s.d.. The system was also used for the determination of trace metals in urine. 

Alternatively, water can be pumped from an aquifer through sorption columns and reinjected into the groundwater system. In this context, sorption means any... 

It may also be economical to remove the inhibitory product directly from the ongoing fermentation by extraction, membranes, or sorption. The use of sorption with simultaneous fermentation and separation for succinic acid has not been investigated. Separation has been used to enhance other organic acid fermentations through in situ separation or separation from a recycled side stream. Solid sorbents have been added directly to batch fermentations (18,19). Seevarantnam et al. (20) tested a sorbent in the solvent phase to enhance recovery of lactic acid from free cell batch culture. A sorption column was also used to remove lactate from a recycled side stream in a free-cell continuously stirred tank reactor (21). Continuous sorption for in situ separation in a biparticle fermentor was successful in enhancing the production of lactic acid (16,22). Recovery in this system was tested with hot water (16). 

Chen, H.-W., Fang, Z.-L., Combination of flow injection with capillary electrophoresis. Part 3. Online sorption column preconcentration capillary electrophoresis system. Anal. Chim. Acta 1997, 355(2-3), 135-143. 

The general merits of FI separation and preconcentration summarized in Chapter 1 are all well demonstrated by FI sorption column techniques. The technique is inherently easier to operate than other separation methods, and the equipment generally more robust. An additional benefit over other separation techniques is its extremely high versatility, owing to the availability of a broad range of choice for different sorbents, complexing systems, and eluents. However, there are some restrictive features which are characteristic... 

Fig.4.4 Schematic diagram of FI hydride generation AAS system with on-line removal of metal interfer-ents using on-line sorption column.

The dual-column and single-column ion-exchange precoilcentration flame AAS systems as well as the DDC-Cis sorbent extraction flame AAS and ETAAS systems used for the determination of cadmium were also used for the determination of copper in water samples. The detection limit for the dual-column system was 0.07-0.09 /ig l at 60 samples h [7] for the sorbent extraction preconcentration flame AAS system, 0.2 /xg r at 120 samples h [9] for the sorbent extraction ETAAS system, 0.02 /xg 1 at approximately 20 samples h [10]. The sensitivity of sorption column preconcentration methods with flame AAS detection should be sufficient for the determination of copper in most natural water samples. 

PERIODIC COUNTERCURRENT SORPTION IN MULTIPLE-COLUMN SYSTEMS... 

Fixed-bed sorption eolumns can be operated as single units or multiple units. The columns can operate by upflow or downflow, and multiple-column systems can operate in series or parallel. Figure 15.23 shows eolumns in series operating downflow. Each bed can be replaced as a eomplete, separate unit. When breakthrough occurs in the last column, the first column will be in equUibrium with the influent, thus achieving maximum adsorbent sorption capacity and utilization. This may be as a result of economic necessity. This first column will then beeome the last eolumn in the system. 

In preparative selective chromatography, the formation of broad zones of the substances is determined by the formation of sharp boundaries of each zone. The formation of these sharp boundaries of substance zones in column sorption processes for systems in which the interphase transfer is limited by substance diffusion in sorbent grains [104, 122, 123] is determined by the dimensionless criterion X ... 

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