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Physical & Chemical properties

Partition coefficient

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Description of key information

The partition coefficient of the test material was determined to be 1.4 x 10⁷. The log Pow of the test material was determined to be 7.1.

Key value for chemical safety assessment

Log Kow (Log Pow):
7.1
at the temperature of:
35 °C

Additional information

There are two studies available to address this endpoint, one key and one supporting.

In the key study, the partition coefficient of the test material was investigated using the HPLC method in a study which was performed under GLP conditions and in accordance with the standardised guidelines OECD 117, EU Method A.8 and US EPA OPPTS 830.7570. The study was awarded a reliability score of 1 in accordance with the criteria of Klimisch et al. (1997).

Following calculation of the pKa values of the test material, it was decided to perform the HPLC method at neutral pH in order to ensure that the test material was in its non-ionised form.

Solutions of reference materials and the test material were analysed. The capacity factor (k') of each compound was calculated from its retention time. The log k’ values of the reference materials were plotted against the known log Pow values. A linear regression program was used to calculate the calibration curve. Linear regression analysis was performed using the least squares method. The coefficient of correlation (r) was calculated. The log Pow value for the test material was calculated by substituting its mean log k’ in the calibration curve. The value of log Pow obtained from duplicate measurements was within ± 0.1 log units.

Under the conditions of the study, the partition coefficient of the test material was determined to be 1.4 x 10⁷. The log Pow of the test material was determined to be 7.1. The determination was carried out at neutral pH; the column temperature was 35 °C.

In the supporting study, the partition coefficient of the test material was estimated using the KOWWIN model v1.68 (EPI Suite v4.11); this study was awarded a reliability score of 2 in accordance with the criteria of Klimisch et al. (1997).

KOWWIN estimates the partition of an organic compound by identifying fragments of the structure and summing the known partition coefficients of these fragments. The material fell within the molecular weight range of the training set of the model. The functional groups of the material were included in the training set and the instances of each fragment of the material did not exceed the maximum count of that fragment in the training set data.

The Log Kow was calculated to be 6.3913.