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Partition coefficient

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Description of key information

Log Kow: 6.2 at 20°C (QSAR)

Key value for chemical safety assessment

Log Kow (Log Pow):
6.2
at the temperature of:
20 °C

Additional information

A predicted log Kow value of 6.2 at 20°C was determined for the substance using a validated QSAR estimation method. The result is considered to be reliable. The calculated log Kow value was supported by a measured log Kow of >6.5 extrapolated to 7.84 which was determined using a relevant form of the HPLC test method, but lacking some corrective adjustment that would be necessary to validly interpret the result. For organosilicon substances of this type, validation studies have been conducted to develop appropriate HPLC estimation methodology to determine log Kow. In addition to non-standard mobile phase, a specific adjustment must be applied to correct the resulting measured log Kow.

Octamethyltrisiloxane (L3, CAS No. 107-51-7) is a structural analogue of the submission substance, 1,1,1,3,5,5,5-heptamethyltrisiloxane (H-L3, CAS No. 1873-88-7). L3 has a measured log Kow of 6.6 at 25°C using OECD 123 test method (slow stirring method) and it is expected that H-L3 should have a slightly lower log Kow due to its smaller molecular volume. Therefore, the predicted log Kow result for H-L3 was selected as key study and used for assessment purposes.