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Partition coefficient

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Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
from 2020-02-12 to 2020-05-07
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:
2004
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method A.8 (Partition Coefficient - HPLC Method)
Version / remarks:
440/2008/EC, 30 May 2008
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:
< 1.3
Temp.:
20 °C
pH:
7

The retention time is described by the capacity factor k given by the expression: k = tR-t0/t0

The octanol/water partition coefficient of the test item can be computed by experimentally determining its capacity factor k and then inputting k into the following equation: log POW = a + b x log k

 

1st run

2nd run

mean value

t0 (min)

2.672

2.674

2.673

 

reference item 1st run

tR

k

log k

log POW

4-Methoxyphenol

3.202

0.198

-0.704

1.3

Phenol

3.317

0.241

-0.618

1.5

p-Cresol

3.553

0.329

-0.483

1.9

4-Chlorophenol

3.680

0.377

-0.424

2.4

1-Naphthol

4.044

0.513

-0.290

2.7

4-Phenylphenol

4.276

0.600

-0.222

3.2

The first measurement and the linear regression of the calibration graph leads to an equation for the log POW of: log POW = 3.943 + 3.890 x log k

reference item 2nd run

tR

k

log k

log POW

4-Methoxyphenol

3.205

0.199

-0.701

1.3

Phenol

3.318

0.241

-0.617

1.5

p-Cresol

3.553

0.329

-0.483

1.9

4-Chlorophenol

3.683

0.378

-0.423

2.4

1-Naphthol

4.045

0.513

-0.290

2.7

4-Phenylphenol

4.278

0.600

-0.222

3.2

The second measurement and the linear regression of the calibration graph leads to an equation for the log POW of: log POW = 3.946 + 3.903 x log k

test item

tR

k

log k

log POW

POW

1st measurement

3.053

0.142

--

--

--

2nd measurement

3.053

0.142

--

--

--

mean value

--

--

standard deviation

--

--

According to Regulation EC No. 440/2008 method A.8. and OECD Test Guideline 117 the partition coefficient of the test item at 20 °C cannot be determined via interpolation as the retention time is below the retention time of the reference item with the lowest log POW. Therefore, the log POW can only be estimated to be: log POW < 1.3

Conclusions:
The log partition coefficient at 20 °C of the test item was estimated to be < 1.3.
Executive summary:

A study was conducted to determine the log Pow of the test item according to the HPLC method described in OECD Guideline No. 117 (2004) and EU Regulation No. 440/2008. Because the retention time of the test item was below the retention time of the reference substance with the lowest log Pow, no distinct value could be defined. The log Pow of the test item was determined to be < 1.3.

Endpoint:
partition coefficient
Type of information:
(Q)SAR
Adequacy of study:
key study
Study period:
2020-06-19
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and 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: ECHA Guidance on information requirements and chemical safety assessment Chapter R.6: QSARs and grouping of chemicals
Version / remarks:
May 2008
Deviations:
no
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: NCCOC(OCCN)(C)C
Key result
Type:
log Pow
Partition coefficient:
-0.58
Temp.:
25 °C
Remarks on result:
other: QSAR predicted value. The substance is (not) within the applicability domain of the model.

KOWWIN Program (v1.68) Results:

===============================

 

Log Kow(version 1.68 estimate): -0.58

 

SMILES : NCCOC(OCCN)(C)C

CHEM   :

MOL FOR: C7 H18 N2 O2

MOL WT : 162.23

 

TYPE 

 NUM

        LOGKOW FRAGMENT DESCRIPTION        

  COEFF 

  VALUE

Frag 

  2 

  -CH3    [aliphatic carbon]               

 0.5473 

  1.0946

Frag 

  4 

  -CH2-   [aliphatic carbon]               

 0.4911 

  1.9644

Frag 

  1 

  C     [aliphatic carbon - No H, not tert]

 0.9723 

  0.9723

Frag 

  2 

  -O-     [oxygen, aliphatic attach]       

-1.2566 

 -2.5132

Frag 

  2 

  -NH2    [aliphatic attach]               

-1.4148 

 -2.8296

Factor

  1 

  C-O-C-O-C  structure  correction         

 0.5036 

  0.5036

Const

    

  Equation Constant                        

        

  0.2290

 

Log Kow   =  -0.5789

Conclusions:
Using KOWWIN v1.68 the logPow of the test item was calculated to be -0.58 at 25 °C. The substance is within the applicability domain of the model.
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 -0.58 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 is applicable to the query 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 is relevant for the regulatory 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

Using KOWWIN v1.68 the log Pow of the test item was calculated to be -0.58 at 25 °C. The substance is within the applicability domain of the model.

Key value for chemical safety assessment

Log Kow (Log Pow):
-0.58
at the temperature of:
25 °C

Additional information

A study was conducted to determine the log Pow of the test item according to the HPLC method described in OECD Guideline No. 117 (2004) and EU Regulation No. 440/2008. Because the retention time of the test item was below the retention time of the reference substance with the lowest log Pow, no distinct value could be defined. The log Pow of the test item was determined to be < 1.3. Therefore, a QSAR calculation was performed using KOWWIN v1.68. The substance is within the applicability domain. The log Pow of -0.58 at 25 °C derived from the QSAR model is used as key value for chemical safety assessment. The value is supported by the experimental study (consilab, 2020) which estimated a value of < 1.3 at 20 °C.