Three-phase partitioning extraction

Index Entries Recombinant green fluorescent protein GFPuv hydro-phobic interaction chromatography sodium dodecylsulfate polyacrylamide gel electrophoresis three-phase partitioning extraction. 

The purpose of the present work was to determine the thermal stability of the three-phase partitioning (TPP)-extracted recombinant protein, GFPuv, in different buffers, as well as to verify its utility as a quick, accurate, and economical BI for moist-heat treatments (T < 100°C) in different pH conditions. 

Harde SM, Singhal RS (2012) Extraction of forskolin horn Coleus forskohlii roots using three phase partitioning. Sep Purif Technol 96 20-25. doi 10.1016/j.seppur.2012.05.017... 

A solution of 1.0 mmol of 2-acetyl alkenoate in 2.5 mL of CH2C1, is added slowly to a solution of 4.0 mmol of titanium(IV) chloride in 7.5 mL of CH-CL under an atmosphere of nitrogen at — 78 °C. The mixture instantaneously turns deep red. and is stirred at — 78 °C before being quenched by the addition of 5 mL of sat. aq potassium carbonate. The mixture is then partitioned between 10 mL of bt20 and 10 mL of water. The aqueous phase is extracted with three 10-mL portions of Et2(), and the extracts are combined, washed with 10 mL of brine, and dried over anhyd potassium carbonate. Concentration under reduced pressure gives the crude product. Product analysis is by capillary GC. 

This trend can be explained with the following mechanism. In the presence of NAPL, the extracted vapor concentration depends mainly on the vapor pressure of the contaminant. After the disappearance of free NAPL, the extracted vapor concentration becomes dependent on the partitioning of contaminants among the three other phases (see Table 14.3). As the air passes through the pores, the dissolved contaminants volatilize from the soil moisture to the gas phase, causing the desorption of contaminants from the surface of soil particles into the aqueous phase. As a result, the concentration in all three phases decreases, with a consequent decrease in removal rates. 

Some of the disadvantages of the Stille reaction, e. g. the low reactivity of some substrates, separation difficulties in chromatography, and the toxicity of tin compounds, have been ameliorated by recent efforts to improve the procedure. Curran has, in a series of papers, reported the development of the concept of fluorous chemistry, in which the special solubility properties of perfluorinated or partly fluorinated reagents and solvents are put to good use [45]. In short, fluorinated solvents are well known for their insolubility in standard organic solvents or water. If a compound contains a sufficient number of fluorine atoms it will partition to the fluorous phase, if such a phase is present. An extraction procedure would thus give rise to a three-phase solution enabling ready separation of fluorinated from nonfluorinated compounds. 

Hexane (100 mL) is added to the reaction mixture causing more white precipitate to form. The mixture is filtered by suction, and the collected solids are washed with two 50-mL portions of hexane. The combined filtrate and washings are partitioned with 200 mL of a mixture (1 3 v/v) of saturated potassium carbonate solution and water (Note 8). The aqueous phase is extracted with three 200-mL portions of hexane. The combined organic phases are partitioned with 100 mL of saturated sodium chloride, dried thoroughly over anhydrous sodium sulfate and concentrated under reduced pressure to afford 65-75 g of crude product. A small amount of additional crude material can be isolated by continuously extracting the combined aqueous layers with hexane for 3 hr. 

A necessary preface to a description of the procedure is that the solvent and the precipitant must be purified to exhaustion by contact with successive specimens of the acid to be purified. The acid A is dissolved in the minimum amount of solvent S. The precipitant P is then added under isothermal conditions to the solution until roughly one half to three quarters of A has been precipitated. At this stage there is a three-phase system present (vapour and two liquids) with three (or more) components (A, S, and Imp where Imp denotes an impurity), and the impurities are partitioned between A and the mixture of S and P. This mixture is separated from A by decantation or syphoning, A is redissolved in S and reprecipitated by the addition of P. At all stages of this process the mixtures must be stirred efficiently but so gently that an emulsion is not formed. It happens quite often that an acid A with a melting point near or above ambient temperature will start to crystallise after the first or second extraction. 

A three-phase liquid-liquid partitioning consisting of hexane, acetonitrile, and dichloromethane has also proven to be a preferred cleanup method for diethylstilbestrol and zeranol (455), trenbolone and epitrenbolone (445), trenbolone and nortestosterone (446), and melengestrol residues (456) in tissues. Following adjustment of the initial aqueous acetonitrile sample extract at pH 13, most of the polar and ionic acidic matrix components were directed into the aqueous layer during the partitioning process, while the low-polarity components were extracted... 

In addition, residues of corticosteroids can be cleaned up through application of a three-phase liquid-liquid partition system consisting of acetonitrile, hexane, and dichloromethane. Since its inception, this procedure has been used successfully to perform a fast, crude fractionation of tissue components and drugs extracted from tissue homogenates into the aqueous acetonitrile supernatant. Non-... 

Enantiomeric purity was determined to be 96-98% by 1H NMR analysis of the Mosher esters4 of the alcohols 4 and ent-4 obtained by reduction of the aldehydes 5 and ent-5. To an ice-cold solution of aldehyde 5 (0.10 g, 0.44 mmol) in 5 mL of methanol was added solid sodium borohydride (33 mg, 0.88 mmol). After the mixture was stirred for 30 min at this temperature, the TLC in (7 3) cyclohexane-ethyl acetate showed the clean formation of the alcohol 4. The mixture was treated with 0.05 mL of acetone and concentrated to dryness under reduced pressure. The residue was partitioned between water (10 mL) and ethyl acetate (10 mL) and the phases were separated. The aqueous phase was extracted with three 10-mL portions of ethyl acetate. The combined organic phases were dried with anhydrous sodium sulfate and concentrated under reduced pressure. The residue was purified by flash... 

Partitioning of components between two immiscible or partially miscible phases is the basis of classical solvent extraction widely used in numerous separations of industrial interest. Extraction is mostly realized in systems with dispergation of one phase into the second phase. Dispergation could be one origin of problems in many systems of interest, like entrainment of organic solvent into aqueous raffinate, formation of stable, difficult-to-separate emulsions, and so on. To solve these problems new ways of contacting of liquids have been developed. An idea to perform separations in three-phase systems with a liquid membrane is relatively new. The first papers on supported liquid membranes (SLM) appeared in 1967 [1, 2] and the first patent on emulsion liquid membrane was issued in 1968 [3], If two miscible fluids are separated by a liquid, which is immiscible with them, but enables a mass transport between the fluids, a liquid membrane (LM) is formed. A liquid membrane enables transport of components between two fluids at different rates and in this way to perform separation. When all three phases are liquid this process is called pertraction (PT). In most processes with liquids membrane contact of phases is realized without dispergation of phases. 

To a cold (— 78 °C) solution of 2.00 mmol of LiOBn [prepared from 310 pL (324 mg 3.00 mmol) of redistilled BnOH and 2.00 mmol of BuLi (1.59 M in hexane)] in 6.0 mL of dry THF is added via cannula a precooled ( — 78 °C) solution of 1.00 mmol of the imide 2 in 4.0 mL of THF. Residual imide is rinsed in with two 2-mL portions of THF, and the resulting solution stirred at — 50 CC for 2.0-50 h prior to quenching with 6 mL of aq pH 7 phosphate buffer. The mixture is partitioned between H20 and CH2C12. The aqueous phase is extracted with three portions of CH2C12 and the organic phases are combined, dried over MgS04 and evaporated in vacuo. The crude product 5 is purified by MPLC. 

Nonporous membrane techniques involve two or three phases separated by distinct phase boundaries. In three-phase membrane systems, a separate membrane phase is surrounded by two different liquid phases (donor and acceptor) forming a system with two phase-boundaries and thus two different extraction (partition) steps. These can be tailored to different types of chemical reactions, leading to a high degree of selectivity. The membrane phase can be a liquid, a polymer, or a gas, and the donor and acceptor phases can be either gas or hquid (aqueous or organic). Liquid membrane phases are often arranged in the pores of a porous hydrophobic membrane support material, which leads to a convenient experimental system, termed supported liquid membrane (SLM). There are several other ways to arrange a hquid membrane phase between two aqueous phases as described below. 

In the direct extraction mode, the SPME partitioning resembles liquid-liquid extraction and, besides the type of fiber coating used, parameters important for optimal recovery are. e.g. agitation technique and pH. Eor headspace SPME, the most important parameters are the vial volume, the headspace-to-sample voliune ratio and the equilibrium temperature, i.e. similar parameters as in traditional HS [24,25]. Although the theoretical treatment of SPME relies on extraction under equihbrium conditions, it is not necessary to estabhsh full equihbrium to perform quantitative analysis. It was shown by Ai that quantitative data can be obtained from both two-and three-phase systems imder non-equilibrium conditions [26-28]. This ex-... 

Solid-phase microextraction is controlled by diffusion rates and partition effects. In typical quantitative analyses, for this technique to be reproducible, the extraction process should continue until the partitioning events reach equilibrium and all variables affecting the partitioning must be controlled. For a two-phase system, the extraction is dependent on the analyte s partition coefficient and the volumes of the solid phase and the water. In the headspace technique, equilibrium must be reached between all three phases the water, the vapor, and the solid phase. 

It is a difficult task to isolate the higher actinides in the HLW, particularly to separate them from the lanthanides, because these elements all are present in solution as trivalent ions of similar size and therefore have very similar chemical properties. The separation methods utilize their slightly different complex forming abilities in techniques such as solvent extraction, ion exchange, and reversed phase partition chromatography. Three solvent extraction processes have been run on a larger experimental scale ... 

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