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Physical & Chemical properties

Partition coefficient

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Description of key information

log Pow – experimental value (HPLC method): 8.2 – 9.6 (avg = 8.9, but not considered reliable thus log Pow > 6.5)
log Pow - calculated from weight-averaged log Koc value: 6.52
log Pow - calculated using KOWWIN v1.68 (weight-averaged value): 6.87
log Pow - calculated using KOWWIN v1.68 (individual constituents): 5.91 – 7.72 (avg = 6.81)
log Pow - calculated using fragment calculation methods (Leo and Hansch, Roberts): 7.19 – 8.43 (avg of the individual values = 7.81)

Key value for chemical safety assessment

Log Kow (Log Pow):
7.07
at the temperature of:
25 °C

Additional information

The log Pow of the substance Alcohols, C16-18, ethoxylated, < 2.5 EO (CAS 68439-49-6) was determined experimentally using the HPLC method according to OECD Guideline 117. The partition coefficients for single components were determined to be in the range log Pow = 8.2 - 9.6. Since a reference substance with log Pow= 5.7 (triphenylamine) was chosen as upper limit for the regression curve, instead of 2,4 -DDT (log Pow =6.5) and due to the fact that the HPLC Method (OECD Guideline 117, EU A.8) enables log Pow to be measured between 0 and 6.5 (Guidance R7a), the obtained values are questionable. Based on the data obtained by HPLC measurement, the overall partition coefficient is deduced to be at least > 6.5. Due to this limitation, the result is not considered for the derivation of the key value for chemical safety assessment.

Therefore, the key value for chemical safety assessment is derived in a weight-of-evidence approach from the various calculated log Pow values (average of values: 6.52, 6.87 and 7.81) for Alcohols, C16-18, ethoxylated, < 2.5 EO (CAS 68439-49-6).

 

The following types of calculations were applied:

1. a combination of calculations according to Leo and Hansch (1979) and Roberts (1991) as cited in the HERA report on AE (2009); the average of the overall range (log Pow 6.03 – 8.43) based on the individual values, i.e. log Pow = 7.32 , was used as input value for derivation of the key value

2. based on weight-averaged log Koc values using the TGD equation for predominantly hydrophobic substances: log Koc = 0.81 log Pow + 0.10 thus log Pow = (log Koc – 0.10)/0.81 (2003 EU Technical Guidance Document on Risk Assessment Part III, Chapter 4, Section 4.3, pp 24 – 27)

3. based on EPIsuite v 4.10, KOWWIN v 1.68 log Pow values for (possible) individual constituents of the substance; a weighting based on normalized composition was applied to derive a log Pow value for the whole substance. Only the weight-averaged value was used as input value for derivation of the key value for chemical safety assessment.