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Partition coefficient

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partition coefficient
Type of information:
Adequacy of study:
key study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
The results were obtained for the known constituents of lime oil, combining empirical and calculated results (estimated by the QSAR Kowwin v 1.67). The constituents of lime oil cold-pressed fall within the applicability domain of the model. The results provided are adequate for the purpose of Classification and Labelling
Justification for type of information:
QSAR prediction: migrated from IUCLID 5.6
Reason / purpose for cross-reference:
reference to same study
no guideline followed
Principles of method if other than guideline:
The partition coefficient of a NCS has little meaning. The range of Log Kow was based on empirical results for limonene and for the constituents the results were predicted based on structural molecular fragments by the KOWWIN program of EPIWIN.

Calculated and measured data on the constituents are obtained from Kowwin v1.67. Figure 1 (attached as a picture) shows that most measured values are lower than the estimated values. It is also clear from the figure that for many constituents, measured log Kow values vary. Sometimes this variation is more than one log unit, especially for the more hydrophobic constituents with a log Kow > 4. It is generally recognized that the log Kow determination of more hydrophobic substances is easily prone to experimental flaws and that for this group it is important to use adequate methods designed to determine higher log Kow values.

This is considered valid because of the variation of measured log Kow values for the constituents, the unknown method of determination and because the calculated log Kow are generally more conservative (higher) than the measured log Kow.
GLP compliance:
Type of method:
other: Calculation by estimation and empirical for major constituent
Partition coefficient type:
Key result
log Pow
Partition coefficient:
3.33 - 7.12
Remarks on result:
other: The model does not provide Temp or pH data for the prediction.
Details on results:
No data

Substance CAS Fraction Estimated log Kow)
D-limonene 5989-27-5 0.44 4.38 (measured, Griffin et al 1999)
Citral 5392-40-5 0.03 3.45
Myrcne B 123-35-3 0.01 4.88
γ-terpinene 99-85-4 0.1 4.75
alpha-pinene 7785-70-8 0.02 4.27
Beta-Pinene 127-91-3 0.1 4.35
Neryl Acetate 141-12-8 0.01 4.48
Sabinene 3387-41-5 0.03 4.69
Alpha-Terpineol 98-55-5 0.07 3.33
Terpinolene 586-62-9 0.06 4.88
5-Geranoxy-7-methoxycoumarin 7380-39-4 0.02 5.78
Alpha-Bergamotene 13474-59-4 0.01 6.57
Alpha-Terpinene 99-86-5 0.01 4.75
Furocomarins N/A 0.03 N/A
Beta-Bisabolene 495-61-4 0.01 7.12
Farnesene 502-61-4 0.01 5.77
Para-Cymene 99-87-6 0.01 4.00
 Cineoles (1,4- and 1,8 -)  470 -67 -7  0.04  3.13
The log Kow range of the constituents of lime oil is 3.13 - 7.12. The percentage of constituents with log Kow >4 is 84%.
Executive summary:

Log Kow was estimated for the constituents of Lime Oil using the program KOWWIN of EPIWIN. The validity of the approach was checked by comparison of measured and predicted values for related substances. Only for the main constituent limonene the empirical log Kow was used.

The log Kow range for lime oil constituents was found to be 3.13 - 7.12. The percentage of constituents with log Kow >4 is 84%.

Description of key information

The log Kow of the constituents of lime Oil is above 4.0 for 84% of the composition.

With log Kow 4.38, limonene represents the group with a high log Kow.

Key value for chemical safety assessment

Log Kow (Log Pow):

Additional information

The predicted log Kow of the constituents of Lime Oil (typical composition) ranges from 3.13 - 7.12. Log Kow is above 4.0 for 84% of the typical constituent composition, whereas the lowest (3.13) and highest (7.12) values were for constituents comprising 4 and 1% respectively. For limonene the log Kow was 4.38.

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