Partition coefficient calculations

Log P is the hydrophobicity (log octanol-water partition coefficient) calculated according to the Ghose-Crippen algorithm.201 dpifA of the carboxylic acid corresponding to the W-acyloxyl substituent. 

A series of experiments was also conducted by Bowman et al. [34] to ascertain the effects of differing environmental factors on the sediment-water interactions of natural estrogens (estradiol and estrone) under estuarine conditions. Sorption onto sediment particles was in this case relatively slow, with sorption equilibrium being reached in about 10 and 170 h for estrone and estradiol, respectively. On the other hand, true partition coefficients calculated on colloids were found to be around two orders of magnitude greater that those on sediment particles. Hence, it was concluded that under estuarine conditions, and in comparison to other more hydrophobic compounds, both estrone and estradiol... 

Assumed source concentrations C0 for four arbitrary elements (column 2), mineral 1-liquid and mineral 2-liquid partition coefficients (columns 3 and 4), residual solid-liquid bulk partition coefficients calculated from mineral abundances listed in Table 9.2. Concentration units are arbitrary. 

Using predictive models for measuring environmental chemodynamics of organic pollutants in complex mixtures requires literature data on partition coefficient values. In some cases the values cited are not strictly experimental, being derived from linear free energy relations, while in others wide variations are reported in experimental values. The main problem is how one should evaluate which values are correct. Thus, Table 2 provides some basis to discriminate between reported values of partition coefficients, as well as predictive equations for partition coefficient calculations [21,62,65-85]. 

It seemed possible to correlate the elution order in reversed-phase liquid chromatography with the octanol-water partition coefficient, logP. For example, the partition coefficients calculated by Rekker s method showed a... 

Authors also performed MLR with MW and HlogPoct, the 1-octanol/water partition coefficient calculated by Huuskonen s simple log Poct model, to examine whether the hypothesis that bundling hydroaffinity and lipoaffinity into a single log Poet parameter is inferior to separating them. The results obtained were as follows (Eq. 44) ... 

The recent work of Wang and Lien (29) illustrates that ion-pair partitioning occurs to a greater extent than previously realized. Partition coefficients calculated from measurements made on partially ionized compounds depend not only on the pH, but on the buffer used. They may vary by more than one log unit. The authors derived equations to correct log P to octanol/water values, but these can still be off by several tenths of a log unit. A preferable solution would be to know the log Pj and account for ion-pair partitioning. 

Richards, N. and Williams, P. B. (1994) Conformation dependent partition coefficient calculations. Chemical Design Automation News 9, 20-25. 

For estimating the air-olive oil partition coefficient, calculate first the air-octanol partition constant from the air-water (Kisw) and octanol-water (Ki0Vi) partition constants given in Appendix C (Eq. 6-11) ... 

Table 4-7 Several examples of estimated values of gas/polyolefin, gas/water, and polyolefin/water partition coefficients calculated using Retention Indices.

Some static headspace methods do not require an external calibration and are based on measurements performed at thermodynamic equilibrium between liquid and gas phase. In the phase ratio variation method (PRV) described by Ettre and Collaborators (1993), the partition coefficient calculation is based on the fact that the headspace concentration changes as a function of the phase volume ratio (gas and liquid phases), while the partition coefficient remains constant. This method has been recently applied to study the interactions between aroma compounds and macromolecules in different food systems (Savary et al. 2006, 2007) but so far not to the wine. 

Machatha, S.G. and Yalkowsky, S.H. (2005) Comparison of the octanol/water partition coefficients calculated by ClogP , ACDlogP and KowWin to experimentally determined values. International Journal of Pharmaceutics, 294, 185-192. 

Initially, the vapor pressure measurements appear to be the most direct, but even here some assumptions are needed. The amount of alcohol in the micellar phase needs to be determined. To do this the difference in vapor pressure between a pure aqueous and a micellar solution is measured. If the ions of the surfactant salts out alcohol, the vapor pressure of pure water is not the correct comparison, and this could lead to lower partition coefficients. Thermodynamic data are well suited for model calculations, and both the models of DeLisi et al. ° ° and Hetu et al. fit the data well. Although in reasonable internal agreement, the partition coefficients calculated from partial molar volumes differ from those calculated from enthalpies the first is 927 or 944, the latter... 

Partition Coefficients Calculated from (a) Equation 6.32, (b) Equation 6.33, and (c) Recommended Experimental Values at 298.15 K... 

It should be noted that the octanol-water partition coefficient calculated from the Law of Distribution Between Phases and the experimental water solubility agrees well with our experimetally determined partition coefficient. This result is expected since the molar solubility of dioxin in both octanol and water is sufficiently low at saturation that there is no significant impact on the activity coefficient of dioxin in either phase. Further, solubilities of octanol in water, and water in octanol are so slight that there is no significant difference between dioxin solubilities for the pure solvents compared to mutually saturated solvents. 

Octanoi-air partition coefficient calculated from KowI aw> where Kow is the octanol-water partition coefficient and Taw is the air-water partition coefficient or unitless Henry s law constant (Kaw = HLC/RT, where HLC = Henry s law constant, R = gas constant 8.319 Pa m /mol and r = 293 K)... 

Distributions of this type are traditionally interpreted as the result of particulate scavenging in surface waters followed by remineralization at depth. Type of distribution contrasts strongly with that of Co, the first series transition metal which is located directly above Rh in the periodic table, illustrates that elements from the same group in the periodic table can exhibit very different chemical behavior. The contrasting behavior of Co and Rh is potentially related to the fact the Co has an active redox chemistry in the marine environment whereas Rh is believed to be stable only as Rh(III) complexes. It is unclear why the upper crustal partition coefficient calculated for Rh is so large (Figure 1) by analogy to other trivalent metals a much lower value would be expected. 

Partition coefficients calculated as the ratio of concenfratlons in full-thickness skin and vehicle at the end of fhe penetration experiments. 

Fig. 14.5 Predicted partition coefficients calculated with the Peng-Robinson eos and various mixing rules for the system CO2-H2O-M MA system as compared to the experimentally obtained values in the high-pressure extraction unit (a) 298 K (b) 313 K (c) 323 K and (d) 333 K.

Table 4 Selected Rmw and ipo lipophilicity parameteis and the values of experimental partition coefficients and partition coefficients calculated by using different theoretical methods.

In the case of TCE, water/air (A /air) and blood/air (Ab/air) partition coefficients calculated at room temperature are equal to 0.24 and 0.90, respectively. Consequently, the blood/water partition coefficient (Ab/w) is 3.75 corresponding to a partition of 73.4% of the total TCE in blood fluid after reaching equilibrium. 

The partition coefficients calculated according to the UNIFAC method are in fairly good agreement with those calculated by the Retention-Index-Method in every case. 

Inadequacy of Partition Coefficient Calculations in Evaluating Bioaccumulation... 

In summary, the tissue-plasma partition coefficient calculated in (21) takes us back to (18) in the Berezhkovskly paper. 

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