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Partition coefficient

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Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
2012-06-21 to 2012-06-22
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)
Version / remarks:
adopted 13th April 2004
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method A.8 (Partition Coefficient)
Version / remarks:
May 2008
Deviations:
no
Qualifier:
according to guideline
Guideline:
EPA OPPTS 830.7570 (Partition Coefficient, n-octanol / H2O, Estimation by Liquid Chromatography)
Version / remarks:
August 1996
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Key result
Type:
log Pow
Partition coefficient:
> 6.5
Temp.:
25 °C
pH:
6.4
Details on results:
In the course of this study the partition coefficient (Pow) of ditetradecyl peroxydicarbonate was determined using high performance liquid chromatography.
Because of the test item properties a short HPLC column and mobile phase with high elution strength had to be applied. Under these circumstances the retention times of the reference items were below 1 minute.
The correlation coefficient R for the relationship between log k and log Pow of the reference item is 0.959.
The short retention times and the relatively high standard deviations (CV%) caused that quality criteria were not met, as values of log Pow derived from individual measurements did not fall within a range of 0.1 log units.
Retention time of ditetradecyl peroxydicarbonate (35.52 minures) is significantly higher than the last eluting standard (DDT) (0.81 minutes); therefore an accurate value of log Pow could not be given. As quality criteria of the calibration data were not met and the estimated partition coefficient of the test item is much more greater than the last eluting standard; the extrapolated log Pow value was not calculated, but the result is considered scientifically valid.
The estimated log Pow of ditetradecyl peroxydicarbonate is > 6.5.
Conclusions:
Using the HPLC method the n-octanol/water partition coefficient of ditetradecyl peroxydicarbonate was determined to be much higher than the last eluting standard (DDT). The estimated log Pow of ditetradecyl peroxydicarbonate is > 6.5.
Executive summary:

The partition coefficient (n-octanol/water) of ditetradecyl peroxydicarbonate was estimated using the HPLC method according to EU method A.8, OECD guideline no. 117 and OPPTS guideline 830.7570. The n-octanol/water partition coefficient of ditetradecyl peroxydicarbonate was determined to be much higher than the last eluting standard (DDT). The estimated log Pow of ditetradecyl peroxydicarbonate is > 6.5.

Endpoint:
partition coefficient
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model, but not (completely) falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
Please refer to the QMRF and QPRF files provided under the section attached justification.
Qualifier:
according to guideline
Guideline:
other: REACH guidance on QSAR R.6
Principles of method if other than guideline:
Estimates the log octanol-water partition coefficient, log KOW, of chemicals using an atom/fragment contribution method.
GLP compliance:
no
Type of method:
calculation method (fragments)
Partition coefficient type:
octanol-water
Specific details on test material used for the study:
SMILES: CCCCCCCCCCCCCCOC(=O)OOC(=O)OCCCCCCCCCCCCCC
Key result
Type:
log Pow
Partition coefficient:
13
Temp.:
25 °C
Remarks on result:
other: QSAR predicted value. The substance is not within the applicability domain of the model.

TYPE 

 NUM

       LOGKOW FRAGMENT DESCRIPTION        

 COEFF 

 VALUE

Frag 

 2 

 -CH3   [aliphatic carbon]               

 0.5473 

 1.0946

Frag 

 26 

 -CH2-  [aliphatic carbon]               

 0.4911 

 12.7686

Frag 

 2 

 -OC(=O)O- [carbonate,aliphatic attach]  

-1.0900 

 -2.1800

Factor

 1 

 -C(=O)-O-O-C(=O)- correction            

 1.1000**

 1.1000

Const

    

 Equation Constant                        

        

 0.2290

Conclusions:
Using KOWWIN v1.68 the logPow of the test item was calculated to be 13.0 at 25 °C. The substance is not within the applicability domain of the model. Thus the estimation may be less accurate.
Executive summary:

The logPow was calculated using KOWWIN v1.68 as part of EPISuite v4.11 from US Environmental Protection Agency.

Using KOWWIN v1.68 the log Kow of the test item was calculated to be 13.0 at 25 °C (EPI Suite, 2014).

The adequacy of a prediction depends on the following conditions:

a) the (Q)SAR model is scientifically valid: the scientific validity is established according to the OECD principles for (Q)SAR validation;

b) the (Q)SAR model isapplicable to thequery chemical: a (Q)SAR is applicable if the query chemical falls within the defined applicability domain of the model;

c) the (Q)SAR result is reliable: a valid (Q)SAR that is applied to a chemical falling within its applicability domain provides a reliable result;

d) the (Q)SAR model isrelevant for theregulatory purpose.

 

For assessment and justification of these 4 requirements the QMRF and QPRF files were developed and attached to this study record.

 

Description of the prediction Model

The prediction model was descripted using the harmonised template for summarising and reporting key information on (Q)SAR models. For more details please refer to the attached QSAR Model Reporting Format (QMRF) file. 

 

Assessment of estimation domain

The assessment of the estimation domain was documented in the QSAR Prediction Reporting Format file (QPRF). Please refer to the attached document for the details of the prediction and the assessment of the estimation domain.

Description of key information

QSAR calculation resulted in a logPow value of 13.01.

Key value for chemical safety assessment

Log Kow (Log Pow):
13
at the temperature of:
25 °C

Additional information

Using the HPLC method the n-octanol/water partition coefficient of ditetradecyl peroxydicarbonate was determined to be much higher than the last eluting standard (DDT). The estimated log Pow of the test item is > 6.5.

QSAR calculation resulted in a logPow value of 13.01.

Since it is technically not feasible with the available experimental methods to determine partition coefficients > 8 (ECHA guidance on CSA & IR, 7a (2017)), the modelled value of 13 is considered to be more reliable and thus applied as key value for the CSA.