Selective extracting agents

Research should continue on traditional separation methods. For example, there is a continuing need for more selective extraction agents for liquid-liquid and ion-exchange extractions. High-temperature processes that use liquid metals or molten salts as extraction agents should have potential in nuclear fuel reprocessing and... 

Griiner, B., Plesek, J., Baca, J. et al. 2002. Crown ether substituted cobalt bis(dicarbollide) ions as selective extraction agents for removal of Cs + and Sr2 + from nuclear waste. New J. Chem. 26 (7) 867-875. 

Lipophilic crown compounds as selective extracting agents 88ZC1. Metal ion selective color reactions with crown ether dyes 88-YGK96. 

Crown-ether functionalized acylpyrazolones (30) and (31) have been synthesized and found effective as metal-ion-selective extraction agents.192 Two chelating acylpyrazolone moieties were linked to each other by aliphatic chains (32) or aromatic moieties (33) and shown to be able to... 

Some of the areas in which supercritical CO2 (SCCO2) is commercially important are summarized in Figure 8.9. Extraction processes in the food, tobacco (nicotine extraction) and pharmaceutical industries dominate. Supercritical CO2 is a selective extracting agent for caffeine, and its use in the decaffeination of coffee and tea was the first commercial application of a supercritical fluid, followed by the extraction of hops in the brewing industry. Solvent extractions can be carried out by batch processes, or by a continuous process in which the CO2 is recycled as shown schematically below ... 

Determination of trace impurities in uranium is one of the potentially major applications of ICP-MS because the mass spectrum of uranium from an ICP is very simple. Spectral overlap with analyte signals is not a problem, as is often the case in many optical emission methods. In ICP-MS, however, this analysis is often limited by suppression of analyte signal induced by the large excess of uranium in the solution. Various selective extracting agents (e.g, tri-n-octylphosphine oxide) have been... 

The procedure followed entails the removal of gross interferences by solvent extraction, and the selective extraction and concentration of the trace metal by use of a chelating agent. The alloy used should not contain more than 0.1 g of copper in the sample weighed out. 

Solvent acts as a selective extractant, retaining the sample because of its higher affinity for the solvent compared to the gas. Solutions of chemical or physical complexing agents nay be used to improve the extraction efficiency. 

The Zn-N3imide interaction has been used to selectively extract imide-containing nucleosides and nucleotides into lipophilic media (39). Hexadecyl-derivatized Zn2+-cyclen was shown to extract dT from an aqueous solution containing a mixture of C, A, and G nucleobases. The antiviral agent AZT (3 azido-3 deoxythymidine) could also be extracted into CHCI3 from neutral aqueous solutions. Transport across a lipophilic layer was also shown, using acidic conditions, to promote the release of dT and AZT (Fig. 9). 

David et al. [184] have shown that cool on-column injection and the use of deactivated thermally stable columns in CGC-FID and CGC-F1D-MS for quantitative determination of additives (antistatics, antifogging agents, UV and light stabilisers, antioxidants, etc.) in mixtures prevents thermal degradation of high-MW compounds. Perkins et al. [101] have reported development of an analysis method for 100 ppm polymer additives in a 500 p,L SEC fraction in DCM by means of at-column GC (total elution time 27 min repeatability 3-7 %). Requirements for the method were (i) on-line (ii) use of whole fraction (LVI) and (iii) determination of high-MW compounds (1200 Da) at low concentrations. Difficult matrix introduction (DMI) and selective extraction can be used for GC analysis of silicone oil contamination in paints and other complex analytical problems. 

The presence in dyehouse effluents of typical dye-complexing metal ions is an environmentally sensitive issue, such metallic contamination arising mostly from the decomposition of metal-complex dyes [26]. The synthetic complexing agent cucurbituril (section 10.3.2) can be used to selectively extract such metal ions from the effluent. 

Cyclic carbonate [wt.%] Extraction agent [wt.%] NOP [wt.%] Conversion of trans-4-octene [%] Selectivity to M-nonanal [%] Rh leaching [%] P leaching [%]... 

Table 11). The system performance was very stable, regardless of the mediator or extracting agent. These results demonstrate that the TMS approach can indeed lead to highly active and selective processes with a remarkably efficient separation. 

Combariza MY, SavariarEN, Vutukuri DR, Thayumanavan S, Vachet RW. Polymeric inverse micelles as selective peptide extraction agents for MALDI-MS analysis. Anal Chem 2007 79 7124-7130. 

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