Fluid phase partition coefficient

For determination of fluid phase partition coefficients, K, one may take a symmetric approach that uses Equation of States (EOS) for all fluid phases or an unsymmetrical approach that makes use of liquid activity models for the liquid phase retaining the equation of state models for the gas phase. 

The diffusion coefficient in these phases D is usually considerably smaller than that in fluid-filled pores however, the adsorbate concentration is often much larger. Thus, the diffusion rate can be smaller or larger than can be expected for pore diffusion, depending on the magnitude of the fluid/solid partition coefficient. 

The constant is not a tme partition coefficient because of difference, — V, includes the soflds and the fluid associated with the gel or stationary phase. By definition, IV represents only the fluid inside the stationary-phase particles and does not include the volume occupied by the soflds which make up the gel. Thus is a property of the gel, and like it defines solute behavior independently of the bed dimensions. The ratio of to should be a constant for a given gel packed in a specific column (34). 

Jonsson, J. A., Vejrosta, J., Novak, J. (1982) Air/water partition coefficients for normal alkanes (n-pentane to n-nonane). Fluid Phase Equil. 9, 279-286. 

Bakierowska, A.-M., Trzeszqzynski, J. (2003) Graphical method for the determination of water/gas partition coefficients of volatile organic compounds by a headspace gas chromatography technique. Fluid Phase Equil. 213, 139-146. 

Ryu, S.-A., Park, S.-J. (1999) A rapid determination method of the air/water partition coefficient and its application. Fluid Phase Equil. 161, 295-304. 

Vejrosta, J., Novak, 1, Jonsson, J.A. (1982) A method for measuring infinite-dilution partition coefficients of volatile compounds between the gas and liquid phases of aqueous systems. Fluid Phase Equil. 8, 25-35. 

The most common partition coefficient encountered in environmental work (Sect. 2.1.4) is the octanol water partition coefficient (K0VI) and the solid phase carbon-water partition coefficient (Koc). A partition coefficient for dissolved organic matter-water (i. e., Kd ()M) or dissolved organic carbon-water (i. e., Kd oc) occasionally appears in the literature. In the case of PCBs, Boyd and Sun [378] defined a partition coefficient for residual transformer oil and water as Kd oil, while Sun and Boyd [379] defined a coefficient for PCB dielectric fluid-water as Kd pen-These authors [378,379] identified a total partition coefficient that com-... 

Hydrophobic pollutants such as PCBs often partition into lipid rather than into water. The K0w measures this partitioning. This coefficient provides an indication of the degree to which a pollutant accumulates into fatty tissues and any organic phase. This coefficient is especially useful for determining the release of PCBs from mineral oil transformer fluids, and Hawker and Connell [391] pro-... 

Petty and Orazio (1996) developed an interesting variation in SPMD liquid phases. The approach consisted of both LDPE and silastic ffibes containing silicone fluid (50 cSt or 3200 MW) with 3% by weight PX-21 activated carbon. The presence of the activated carbon enhanced retention of planar molecules such as PAHs and the silicone fluid remains liquid at temperatures below freezing. However, the partition coefficients of HOCs for this type of silicone fluid are much lower than for triolein. 

Figure 19.16 Spherical structure (particle, bubble, droplet) with radius r0 surrounded by a concentric fluid boundary layer with thickness 5. r is the spherical coordinate. The concentration inside the sphere is Cs. There is a phase change at the surface of the sphere with the equilibrium partition coefficient KSlf = Csl Cp Cp is the fluid concentration in equilibrium with Cs.

The partition coefficient or its logarithm serves as a quantitative measure of a compound s lipophilicity. For pharmaceuticals, water and 1-octanol are the two solvents used most frequently to measure lipophilicity. The two-phase octanol/water system closely models the cell membrane/interstitial fluid interface. While Lipinski s rules do not specify a minimum lipophilicity, a log P value of 5 or less prevents a drug from effectively hiding within membranes. 

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