Salt partition recovery

Recovery of Proteins from Polyethylene Glycol-Water Solution by Salt Partition... 

PEG-water solution, 99f protein recovery by salt partition, 107... 

A gas liquid chromatographic (GLC) method was described for determining residues of Bayer 73 (2-aminoethanol salt of niclosamide) in fish muscle, aquatic invertebrates, mud, and water by analyzing for 2-chloro-4-nitroaniline, a hydrolysis product of Bayer 73 [83]. Residues were extracted with acetone-formic acid (98 + 2), and partitioned from water samples with chloroform. After sample cleanup by solvent and acid base partitioning, the concentrated extract was hydrolyzed with 2N NaOH and H202 for 10 min at 95°C. The 2-chloro-4-nitroaniline was then partitioned hexane ethyl ether (7 + 3) and determined by electron capture GLC. Average recoveries were 88% for fish, 82% for invertebrates, 82% for mud, and 98% for water at 3 or more fortification levels. 

The last talk in this session, by Andrew Lyddiatt (University of Birmingham, United Kingdom), showed how liquid-liquid extraction can address some of the problems associated with the purification of nanoparticulates (e.g., viral and nonviral gene delivery vehicles). Nanoparticles (particle size range 20-150 nm) with low diffusivity and low molalities in culture feedstocks pose unique process engineering problems in the design and implementation of selective recovery and formulation operations. This paper demonstrated how aqueous two-phase partition systems (polymer-polymer and polymer-salt) can circumvent the process bottlenecks posed by the use of... 

Previously, pesticide extraction procedures from grapes and wine in the multiresidue analysis were carried out with polar solvents such as methanol and acetone (Holland and Malcolm, 1992). To increase the recovery of more polar analytes, the extracts were salted out with NaCl, Na2S04 or MgS04, and then partitioned with non-polar solvents such as CH2C12, petroleum ether, etc (Holland and Malcolm, 1992). 

The MD/PEG system offers the combined advantages of low-cost, reduced lower phase viscosities and high density differences for inexpensive polymer-polymer affinity partitioning. When coupled with low-cost affinity ligands i.e. triazine dyes, two-phase aqueous affinity partitioning could be used as the first step in a separation train for the recovery of industrially important enzymes. The bottom phase, which is generally considered to be a waste stream and non-recyclable if dextran or salt is used could be used as a substrate for additional fermentations if maltodextrin is used, thereby aiding the overall economics of the process. 

A significant amount of work has demonstrated the feasibility and the interest of reversed micelles for the separation of proteins and for the enhancement or inhibition of specific reactions. The number of micellar systems presently available and studied in the presence of proteins is still limited. An effort should be made to increase the number of surfactants used as well as the set of proteins assayed and to characterize the molecular mechanism of solubilization and the microstructure of the laden organic phases in various systems, since they determine the efficiency and selectivity of the separation and are essential to understand the phenomena of bio-activity loss or preservation. As the features of extraction depend on many parameters, particular attention should be paid to controlling all of them in each phase. Simplified thermodynamic models begin to be developed for the representation of partition of simple ions and proteins between aqueous and micellar phases. Relevant experiments and more complete data sets on distribution of salts, cosurfactants, should promote further developments in modelling in relation with current investigations on electrolytes, polymers and proteins. This work could be connected with distribution studies achieved in related areas as microemulsions for oil recovery or supercritical extraction (74). In addition, the contribution of physico-chemical experiments should be taken into account to evaluate the size and structure of the micelles. 

Solvent extraction methods usually involve partition of a salt-saturated, acidic sample aliquot with an appropriate solvent. Alternatively, the sample may be subjected to a derivatization step and a clean-up extraction prior to the acidic extraction [15]. A major drawback of the extraction procedures is an incomplete recovery of more polar acid metabolites. However, the method is simple and, consequently, more popular. The anion-exchange approach, developed initially by Horning [375], has been subjected to frequent modifications in other laboratories... 

---