Aqueous two-phase systems ATPS

Proteins (BSA or ovomucoid, OVM) have also been successful in the preparative resolution of enantiomers by liquid-liquid extraction, either between aqueous and lipophilic phases [181] or in aqueous two-phase systems (ATPS) [123, 180]. The resolution of d,l-kynurenine [180] and ofloxacin and carvediol [123] were performed using a countercurrent extraction process with eight separatory funnels. The significant number of stages needed for these complete resolutions in the mentioned references and others [123, 180, 189], can be overcome with more efficient techniques. Thus, the resolution of d,l-kynurenine performed by Sellergren et al. in 1988 by extraction experiments was improved with CCC technologies 10 years later [128]. 

A very interesting separation of biomolecules, for example, proteins and enzymes (BSA, lysozyme), in an aqueous two-phase system (ATPS) realized in hollow fiber contactor is suggested in the paper of Riedl and Raiser [72]. Application of ATPS in... 

For the extraction of proteins, aqueous two-phase systems (ATPS) are preferred over organic solvents, which usually denature the proteins and render them biologically inactive. They consist of polyethylene glycol (PEG), and a salt (e.g., potassium phosphate) or dextran in water. At concentrations above a critical value, the mixture separates into two phases—one rich in PEG and the other in dextran or salt. In industrial systems, salts are more commonly used because they are relatively inexpensive as compared to dextran. The MW, charge and surface properties of the protein decide how the protein partitions in the system. The nature of the phase components, the MW of the polymer, and the concentration and type of salt used also affect the distribution. ... 

An alternative concept uses volatile compounds [32] involving combinations of NH3/CO2. These components form aqueous salt solutions with several ionic species such as carbamate and bicarbonate at concentrations up to 45 wt%. These solutes form aqueous two-phase systems ATPS with the usual water-soluble polymers such as poly(ethylene glycol). Because of the high ammonia content, appH-cations are limited to pH 9-10. 

A good example of a bulk separation are the aqueous two-phase systems (ATPS). They can be used as an alternative and efficient approach for purification of biomolecules by partitioning between two liquid phases. ATPS result from the incompatibility of polymers, either between two polymers in water or a polymer solution with a salt solution. In this system, the cells are considered to be immobilized on to one of the phases of the ATPS and the required product is made to partition into the other phase by proper manipulation of the system. ATPS can be used to purify proteins, cells,viruses particles and plasmid DNA. °... 

Aqueous two-phase systems (ATPS) based on hydrophilic ionic liquid l-butyl-3-methylimidazolium chloride and K2HPO4, coupled with RP-HPLC were proposed for analysis of testosterone (T) and epitestosterone (ET) in human urine (He et al., 2005). The method has been reached satisfactory extraction efficiencies 80-90% and detection limits of 1 ng/mL and linear ranges of 10-500 ng/mL for both compounds (Fig.7). 

Aqueous two-phase systems (ATPS) composed of salt solution and ILs can find its utilization in the extraction of certain organic compounds. For example, ATPS formed by... 

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