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Partition coefficient

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Reference
Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Experimental start date: 29 November 2016. Experimental completion date: 16 May 2017
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)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method A.8 (Partition Coefficient - HPLC Method)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Specific details on test material used for the study:
Identification: 2-(1-oxa-4-azaspiro[4.5]dec-4-yl)ethyl methacrylate (CAS 4203-89-8)
Appearance/physical state: extremely pale yellow slightly viscous liquid
Batch: 1609501020
Purity: 94.5%
Expiry date: 05 October 2017
Storage conditions: approximately 4 °C, in the dark
Analytical method:
high-performance liquid chromatography
Key result
Type:
log Pow
Partition coefficient:
3.2
Temp.:
20 °C
pH:
9.6

Partition coefficient of sample

 The retention times, capacity factor and log10Powvalue determined for the sample are shown in the following table:

Injection

Retention time (mins)

Capacity factor (k′)

Log10k'

Log10Pow

1

3.246

1.141

5.73 x 10-2

3.2

2

3.226

1.128

5.24 x 10-2

3.2

Mean log10Pow:         3.2
Partition coefficient:  1.6 x 103

Discussion

The solvent choice for the test item sample solution matrix and the organic component of the mobile phase was acetonitrile, as opposed to the initial recommended solvent of methanol. This selection was a precautionary step to avoid possible alcoholysis / solvolysis of the test item prior to analysis. This was considered to have no impact on the integrity of the test as acetonitrile is also stated as a permitted alternative solvent within the regulatory guidelines and an acceptable correlation was achieved for the calibration reference standards during the determination.

The mobile phase was adjusted to pH 9.6 to ensure the test item was tested in its non-ionized form. The dissociation constant of the tertiary amine functional group was estimated to be 6.0 using the specialized predictive software pKa, Advanced Chemistry Development, Inc., Toronto, Canada, Algorithm Version v12.1.0.50374.

Based on the HPLC evaluation of test item sample solutions prepared in acetonitrile and water, the test item peak monitored was confidently attributed to the parent test item.

  

Conclusions:
The partition coefficient of the test item has been determined to be 1.6 x 103, log10 Pow 3.2.
Executive summary:

Partition Coefficient (n-octanol/water). 1.6 x 103, log10 Pow 3.2, using an HPLC estimation method designed to be compatible with Method A.8 Partition Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 117 of the OECD Guidelines for Testing of Chemicals, 13 April 2004.

Description of key information

The measured log Kow is 3.2. This is supported by a calculated log Kow of 3.58.

Key value for chemical safety assessment

Log Kow (Log Pow):
3.2
at the temperature of:
20 °C

Additional information

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