Measurement, of partition coefficient

R. -S. Tsai, P.-A. Carrupt, and B. Testa, Measurement of Partition Coefficients Using Centrifugal Partition Chromatography. Method Development and Application to the Determination of Solute Properties, American Chemical Society, Washington DC, 1995, pp. 143-154. 

El Tayar, N. Tsai, R.-S. Vallat, P. Altomare, C. Testa, B., Measurement of partition coefficients by various centrifugal partition chromatographic techniques. A comparative evaluation, J. Chromatogr. 556, 181-194 (1991). 

It must be noted that the partition coefficient is not the ratio of the pollutant solubilities in the two pure liquids. This change can result in significant differences, particularly with compounds of low aqueous solubility. The measurement of partition coefficients may be complicated by the involvement of other equilibrium processes such as pKa and pH values. For example, the following reaction shows the dissociation of a monoprotic organic acid ... 

Karl, T., Yeretzian, C., Jordan, A., and Lindinger, W. Dynamic measurements of partition coefficients using proton-transfer-reaction mass spectrometry (PTR-MS), Int. J. Mass Spectrom., 223-224 383-395, 2003. 

Laboratory Extractors. Pilot-Scale Testing, and Scale-Up. Several laboratory units arc useful in analysis, process control, and process studies. The AKUFVE contactor incorporates a separate mixer and centrifugal separator. It is an efficient instrument for rapid and accurate measurement of partition coefficients, as well as for obtaining reaction kinetic data. Miniature mixer-settler assemblies set up as continuous, bench-scale, multistage, countercurrent, liquid-liquid contactors are particularly useful Tor the preliminary laboratory work associated with flow-sheet development and optimization because these give a known number of theoretical stages. 

El Tayar, N., R.-S. Tsai, P. Vallat, C. Altomare, and B. Testa. 1991. Measurement of Partition Coefficients by Various Centrifuge Partition Chromatographic Techniques A Comparative Evaluation. /. Chromatog. 556 181-194. 

The solid phase fugacity meter is a more recent development which allows the direct measurement of partition coefficients for less volatile chemicals (Horstmann and McLachlan, 1992 Tolls and McLachlan, 1994). It involves a brief exposure of the vegetation to a... 

In recent years, the availability of reproducible systems and precision instruments in high-performance liquid chromatography (HPLC) has prompted the application of chromatography in the rapid measurement of partition coefficients. In general, a linear relationship between log P and log K from a set of compounds is required for the interpolation or extrapolation of logP values of additional compounds of congeneric nature, as shown in Eq. (16) ... 

Dearden, J.C. Bresnen, G.M. The measurement of partition coefficients. Quant. Struct.-Act. Relat. 1988, 7, 133-144. 

Measurement of partition coefficients of immiscible layers is particularly easy an example is the addition of to inactive iodine to observe the distribution between an organic solvent and water. The partition coefficient, K = activity per cc in the aqueous laycr/activity per cc in the organic layer. 

MEASUREMENT OF PARTITION COEFFICIENT OF CATECHIN AND/OR EPICATECHIN AND ACTS... 

It should be expected that calculated values of 6jjp correlate better with equilibrium properties of the membranes in aqueous solution than with transport properties. Che of the few such equilibrium measurements that have been published is by Anderson et al (.2J). Their measured partition coefficients (K), diffusion coefficients (D), and reverse osmosis rejection (R) of the organic solutes are shown in Table III for cellulose acetate membranes. Their data for cellulose acetate butyrate was similar and is not shown here. Aqueous solutions of the organic solutes, usually at concentrations of about 10 g 1 , were used in the measurement of partition coefficients by UV absorption. In Table III,... 

Tsai, R.-S., Carrupt, P.-A. and Testa, B. (1995) Measurement of partition coefficient using centrifugal partition chromatography. Method development and application to the determination of solute properties, in Modern Countercurrent Chromatography (eds W.D. Conway and R.J. Petroski), American Chemical Society, New York, pp. 143-154. 

Although any of the designs mentioned above will provide the location of phase boundaries (versus temperature and pressure), it is also important to know the compositions of the two phases in equilibrium. Note that while tie lines (lines connecting phases in equilibrium on T-x or p-x diagrams) are horizontal for simple binary mixtures, this is not true for phase separation in multicomponent systems (most notably polymer-fluid systems where the polymer sample contains chains of various lengths). Consequently, ports which allow withdrawal of samples following phase separation and equilibration are an important feature of view cells. Such ports also allow for the measurement of partition coefficients of solutes between, for example, aqueous and CO2 phases. 

Measurements of partition coefficients are frequently used to determine activity coefficients of solute species. We consider a system consisting of two immiscible solvents, phases 1 and 2 and a solute component 2. At equilibrium,... 

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