Partition of solutes

Partition of solute into a second immiscible liquid (e.g. water) may result in its release if the latter is subsequently exposed to air, e.g. in a sump or effluent drain. 

In summary, this simple example illustrates the partition of solutes during precipitation the colour of an egg shell results from the partitioning of chemicals, some coloured, between the growing shell and the gut of the hen during shell growth. 

The extent to which the ions compete with B for the charged sites (X) will determine their retention. In general, this type of chromatography may be used to separate ionic species, such as organic acids or bases, which can be ionized under certain pH conditions. Besides the reaction with ionic sites on the stationary phase, retention may also be affected by the partitioning of solutes between the mobile and stationary phases, as in reversed-phase chromatography. Thus, even nonionized solutes may be retained on ion-exchange columns. 

Morel, F. M. M., and P. M. Gschwend (1987), "The Role of Colloids in the Partitioning of Solutes in Natural Waters", in W. Stumm, Ed., Aquatic Surface Chemistry, Wiley-lnterscience, New York, pp. 405-422. 

An indirect method for the determination of log Poet was also proposed by Chen et al. [91[. The method is based on the partitioning of solutes between a plasticized PVC film (PVC/dioctyl sebacate) and water (log Pp, ) in 96-well micro-titerplates. For a series of 15 reference compounds with log Poet ranging from 0.5 to 3.2, the authors showed that log Poet was related to log Pp by Equation (5.10) ... 

Leaching the treatment solution in highly weathered formations maintains a depressed solution pH and inhibits additional partitioning of solution-phase metals to the solid phase. 

A companion study52,53 tested the ability of this model to simulate the partitioning of solute molecules between the two phases, governed by their relative lipophilicity. The addition of a small number of solute molecules was made to the initial, random mixture. As the dynamics proceeded, it was... 

Separation by MEKC is based on the differential partitioning of solutes into a pseudo -stationary phase. In general, the pseudo-stationary phase is... 

Three different approaches have been presented for estimating the partitioning of solutes between plastics and liquids. In the context of evaluating the output from these different approaches it is also useful to define the expected experimental ranges and limits for partition coefficients based on the solutes, plastic and contacting liquid phases involved. Table 4-9 shows approximate upper and lower limits for partition coefficients one may normally encounter in plastic/food systems based on the polarities of the solutes, plastics and foods. The table also gives approximate ranges of partition coefficient values for various solutes between typical food contact plastics and liquid phases. 

Liquid-Liquid Chromatography. Liquid-liquid chromatographic (LLC) separations result from partitioning of solute (analyte) molecules between two immiscible liquid phases (10). The liquid mobile and liquid stationary phases ideally have little or no mutual solubility. The stationary liquid phase is dispersed on a column of finely divided support. The use of a nonpolar mobile phase and a polar stationary phase is referred to as normal phase LLC. Under these conditions, less polar solutes are preferentially eluted from the column. Reverse phase chromatography employs a nonpolar stationary phase and a polar mobile phase. Generally, polar compounds elute more rapidly with this technique. Reverse phase chromatography, useful for the separation of less polar solutes, has found increased application in occupational health chemistry. It is optimally suited to the separation of low-to-medium molecular weight compounds of intermediate polarity. 

Abraham MM, Chadha HS, Dixon JP et al. (1994) Hydrogen Bonding. Part 9. The partition of solutes between water and various alcohols. Phys Org Chem 7 712-716 Hansch LA, Elkins C (1971) Partition Coefficients and their uses. Chemical Reviews 71 No. 6 Hansch C, Leo A (1979) Substituent Constants for Correlation Analysis in Chemistry and Biology. John Wiley and Sons, New York... 

For this purpose liposomes are used as lipid phase. Unilamellar liposomes are artificial lipid bilayer vesicles. They can be considered as real model bilayer membranes as they ideally consist of a circular bilayer membrane. The hydrophobic acyl chains are assembled in the hydrophobic core of the liposome whereas the hydrophilic head groups point to the water in the inside and outside of the vesicle. Liposomes can be produced from a variety of lipids and from mixtures of lipids. This possibility allows studying the influence of membrane constituents on the partition of solutes. Kramer et al. (1997) studied the influence of the presence of free fatty acids in membranes on the partition behaviour of propranolol. The influence on a-Tocopherol in membranes on the partition behaviour of desipramine has been reported recently (Marenchino et al. 2004) using a liposome model. 

---