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Partition coefficient

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Description of key information

The partition coefficient 1-octanol/water of 1,5,9-cyclododecantriene was determined as log Kow = 6.80 at 25 °C with the slow stirring method (U.S. EPA Method EPA/600/S-96/005, August 1995).

Key value for chemical safety assessment

Log Kow (Log Pow):
6.8
at the temperature of:
25 °C

Additional information

The partition coefficient of 1,5,9-cyclododecatriene was evaluated in many studies which differ according to the method used. The resulting values for log Kow vary with the method:

 

Shake-flask: 4.10 - 4.50

HPLC: 5.65 - 5.77

Slow stirring: 6.80

 

Before deciding on what procedure to use, a preliminary estimate of the Kow should be obtained from calculation. Available QSAR show that log Kow is > 5. Thus, regarding that only Kow values in the range log Kow between -2 and 4 can be experimentally determined by shake-flask method and that Kow values in the range log Kow between 0 and 6 can be estimated using high performance liquid chromatography method, the value obtained with shake-flask method cannot be valid

 

The shake-flask method is prone to artifacts due to transfer of octanol microdroplets into the aqueous phase. With increasing values of Kow the presence of these droplets in the aqueous phase leads to an increasing overestimation of the concentration of the test substance in the water. That's why its use is limited to substances with log Kow < 4. The slow-stirring experiment is thought to reduce the formation of microdroplets from 1-octanol droplets in the water phase. As a consequence, overestimation of the aqueous concentration due to test substance molecules associated to such droplets does not occur. Therefore, the slow-stirring method is particularly suitable for the determination of Kow for substances with expected log Kow values of 5 and higher, for which the shake-flask method is prone to yield erroneous results. As a consequence, the value obtained with the slow-stirring method performed on 1,5,9-cyclododecatriene was considered as valid: log Kow = 6.80

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