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Partition coefficient

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Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
March - May 2008
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
test item is unstable in water, therefore the hydrolysis product PMA was tested; refer to analogue justification provided in IUCLID section 13
Qualifier:
according to
Guideline:
OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method A.8 (Partition Coefficient - Shake Flask Method)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of method:
flask method
Partition coefficient type:
octanol-water
Specific details on test material used for the study:
- Description: white powder
- Batch number: 8M30N
- Storage conditions: room temperature in the dark upto 04 April 2008, thereafter at approximately 4 °C, over silica gel, in the dark
Analytical method:
photometric method
Key result
Type:
log Pow
Partition coefficient:
<= -2.03
Temp.:
21.5 °C
pH:
5

Due to the dissociation constants of the four carboxylic acid functional groups (determined to be 2.18, 2. 70, 4.40 and 5.45, see Section 9), it was not experimentally feasible to determine the partition coefficient of the test material in a non-ionised form as testing would be required at pH 0.2 or lower. Therefore the definitive test was performed at a nominal pH value of 5, the pH within the environmentally relevant range of 5 to 9 at which ionisation of the test material is minimised and hence solubility in n-octanol is maximised.

Conclusions:
PMDA is unstable in water, therefore the corresponding hydrolysis product Pyromellitic acid (PMA) was tested. The partition coefficient of the test material has been determined to be log Pow <= -2.03 at 21.5°C.
Executive summary:

As the substance to be registered, PMDA, is unstable in water, the corresponding hydrolysis product Pyromellitic acid (PMA) was tested. The study was carried out according to EC method A.8, using the flask method. The partition coefficient of the test material has been determined to be less than or equal to 9.25 x 10E-3 at 21.5 ± 0.5°C / log Pow <= -2.03. Testing was performed at a nominal pH value of 5, that at which ionisation was minimised within the environmentally relevant pH range of 5 to 9.

Endpoint:
partition coefficient
Type of information:
(Q)SAR
Adequacy of study:
supporting study
Study period:
2004
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
accepted calculation method
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)
Deviations:
yes
Remarks:
partition coefficient was calculated
GLP compliance:
no
Key result
Type:
log Pow
Partition coefficient:
2.14
Temp.:
20 °C
Details on results:
The log Pow was estimated based on a calculated water solubility of 519 mg/l at 20°C
Conclusions:
The log Pow was estimated to be 2.14 at 20 °C.
Executive summary:

The partition coefficient log Pow was estimated to be 2.14 at 20 °C (calculated by Kowwin vl. 67, EPI suite v3.11).

Description of key information

As the substance to be registered, PMDA, is unstable in water, the corresponding hydrolysis product Pyromellitic acid (PMA) was tested. The study was carried out according to EC method A.8, using the flask method. The partition coefficient of the test material has been determined to be less than or equal to 9.25 x 10E-3 at 21.5 ± 0.5°C / log Pow <= -2.03. Testing was performed at a nominal pH value of 5, that at which ionisation was minimised within the environmentally relevant pH range of 5 to 9. In addition, the partition coefficient log Pow for PMDA itself was estimated to be 2.14 at 20 °C (calculated by Kowwin vl. 67, EPI suite v3.11).

Key value for chemical safety assessment

Log Kow (Log Pow):
-2.03
at the temperature of:
21.5 °C

Additional information

Source: GLP-report