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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:
05-19-2014 to 05-21-2014
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EPA OPPTS 830.7550 (Partition Coefficient, n-octanol / H2O, Shake Flask Method)
Deviations:
no
GLP compliance:
yes
Type of method:
flask method
Partition coefficient type:
octanol-water
Analytical method:
gas chromatography
mass spectrometry
Key result
Type:
log Pow
Partition coefficient:
6
Temp.:
23 °C
Remarks on result:
other: pH not measured
Details on results:
The determined log Kow values ranged from 5.7 to 6.2 for all six samples. The average log Kow values were 6.1, 5.7 and 6.1 for the 1:1, 1:2 and 2:1 octanol: water ratio. The overall average log Kow was 6.0, and overall RSD% was 3.2%.

The average measured water concentration for replicate 1 of2:1 ratio had calculated RPD of 43%, exceeded the targeted precision of <30%. However, no outliner was identified, and concentration was used for calculate average.

Table 1: Summary of n-Octanol/Water Partition Coefficient Log(Kow) for HFE-7500 

 

Ratio

(n-Octanol: Water)

Rep

HFE-7500

in water phase

(ng/mL) (1)

HFE-7500

in octanol phase

(ng/mL) (1)

Kow

log Kow

Average

log Kow

%RPD

1:1

1

1.68

2610000

1550000

6.2

6.1

2.4

1:1

2

2.33

2560000

1100000

6.0

 

 

1:2

1

5.17

2570000

497000

5.7

5.7

1.5

1:2

2

4.10

2480000

605000

5.8

 

 

2:1

1

2.35 (2)

2270000

966000

6.0

6.1

2.2

2:1

2

1.85

2440000

1320000

6.1

 

 

Overall average

 

 

 

 

 

 

6.0

 

Overall RSD%

 

 

 

 

 

 

 

3.2

 (1)    The average concentration of the two aliquots

(2)    RPD% exceeded the targeted precision of <30%.

 

Conclusions:
Log(Kow) for Novec 7500 was measured to be 6.0 at 23°C under the conditions of the study.
Executive summary:

The n-Octanol/Water Partition Coefficient (log Kow) of HFE-7500 was determined according to U.S EPA guidance document OPPTS 830.7550 "Partition Coefficient (n-Octanol/Water), Shake Flask Method". Duplicate samples of HFE-7500 were prepared in each of the three octanol/water ratios (1:1, 1:2, and 2:1). The six samples were rotated 180 ° about their transverse axis for 100 times to ensure proper mixing of the test system solvents. The samples were then centrifuged at 1500 RPM for 15 minutes, and the aqueous and n-octanol phases were carefully removed. For each test vial, duplicate aliquot of water and n-octanol phase were analyzed using Purge and Trap and Gas Chromatography/ Mass spectrometry. The determined log Kow values ranged from 5.7 to 6.2 for all six samples. The overall average log Kow was 6.0, and overall RSD% was 3.2%. This is a guideline study conducted under GLP compliance. Therefore, it is considered reliable without restrictions and a key study.

Description of key information

Key result for CAS# 297730-93-9:
Log Kow: 6.0 experimentally determined using Shake Flask method.
Key result for PFBA (degradation product), CAS# 375-22-4:
Log D at pH 7: -0.36 predicted by QSAR model implemented through the ACD Labs / log D module.

Key value for chemical safety assessment

Additional information

Discussion for CAS# 297730-93-9:

The n-Octanol/Water Partition Coefficient (log Kow) of HFE-7500 was determined in 2014 according to U.S EPA guidance document OPPTS 830.7550 "Partition Coefficient (n-Octanol/Water), Shake Flask Method". The log Kow for HFE-7500 was measured to be 6.0 at 23°C under the conditions of the study.This is a guideline study conducted under GLP compliance. Therefore, it is considered reliable without restrictions and a key study.

 

A previous experiment using HPLC method was conducted in 2005, yielded a log Kow value of 5.75. This study was considered reliable with restriction and a supporting study.

Discussion for PFBA (degradation product), CAS# 375-22-4:

The partition coefficient, log D, was estimated by use of QSAR simulations for CAS# 375-22-4. The key study calculates a log D of the test substance in the aquatic compartment using proprietary software purchased from ACD/Labs v12.00. This QSAR is based on generally accepted simulation software the use of which has been published in peer-reviewed literature. The software's training set contains a number of fluorinated and perfluorinated chemicals, and in particular includes a closely related ethyl ester and therefore, the test substance is considered to be within the applicability domain of the model. This study is classified as acceptable as a QSAR simulation of log D, which is a relevant parameter for determination of transport and distribution of chemicals in the environment.