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Partition coefficient

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Reference
Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Principles of method if other than guideline:
Fast gradient, Reveresed-Phase HPLC method for the estimation of the lipophilicity of susbtances using as a reference substance the test material in interest.
GLP compliance:
not specified
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Type:
log Pow
Partition coefficient:
ca. 2.71
Remarks on result:
other: temperature and pH details not available
Details on results:
Chromatographic hydrophobicity index: 81.15Isocratic chromatographic hydrophobicity index: 81.45Gradient retention time: 13.79Hydrogen count bond: 0

There was a good correlation between the experimentally determined and software calculated log P’s for a diverse set of marine natural products.

Conclusions:
LogPow: 2.71
Executive summary:

A fast-gradient HPLC method using a polystyrene-divinylbenzene PRP-1 column was developed to estimate the lipophilicity of substances. Propiophenone was used as a reference compound and its retention time was used to estimated the logPow of other substances. An excellent correlation was found between the results of the experimental determined and the literature log P values for a diverse set of commercially available drugs using the PRP-1 column.

According to the HPLC theory, the phase preference of a single solute can be expressed by the capacity factor k. The sample k values are also related to the volume fraction, φ, of the organic solvent in the mobile phase as: log k = log kw - Sp The intercept log kw corresponds to the retention in pure water as a mobile phase and represents the commonly employed chromatographic hydrophobicity parameter. S is a solute dependent solvent strength parameter specific to the organic modifier on the stationary phase under consideration. Another retention-related parameter has been introduced recently, the chromatographic hydrophobicity index, which value represents the volume fraction of the organic solvent in the mobile phase for which the amount of solute in the mobile phase is equal to that in the stationary phase, i.e. the capacity factor is 1 (log k = 0 The isocratic retention times were measured by using various volume percents of acetonitrile in the mobile phase, preferably bracketing the retention when log k’ = 0 (that is the retention time was close to the double of the dead time). The isocratic hydrophobicity index was calculated from the slope (S) and the intercept (log k’w) values of the straight lines obtained by plotting log k’ vs φ, based on minimum three points and r > 0.99. The gradient retention time (Tr) was measured under the gradient profile, which included a 15 min linear acetonitrile gradient from 0 to 100 %. The chromatographic hydrophobicity index (CHI) method used fast-gradient reversed phase HPLC to model octanol/water partitioning of a compound by correlating the retention time with the percentage of acetonitrile required to achieve an equal distribution of the compound between the mobile and stationary phases.

Conclusion

The log Pow of the substance is 2.71.

Description of key information

log Pow: 2.71

Key value for chemical safety assessment

Log Kow (Log Pow):
2.71

Additional information

A fast-gradient HPLC method was developed to estimate the lipophilicity of substances; propiophenone was used as a reference compound and its retention time was used to estimated the logPow of other substances. The log Pow of the substance has been indicated at 2.71.

Further data are available from literature sources and the values range from 2.1 to 2.21.