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EC number: 203-537-0 | CAS number: 107-96-0
Partition coefficient
Administrative data
Link to relevant study record(s)
- Endpoint:
- partition coefficient
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 2008.11.26-2008.12.22
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study with acceptable restrictions
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)
- Deviations:
- no
- Qualifier:
- according to guideline
- Guideline:
- EU Method A.8 (Partition Coefficient)
- Deviations:
- no
- GLP compliance:
- yes (incl. QA statement)
- Remarks:
- The Department of Health of the Government of the United Kingdom
- Type of method:
- shake-flask method to: flask method
- Partition coefficient type:
- octanol-water
- Analytical method:
- gas chromatography
- Type:
- Pow
- Partition coefficient:
- ca. 2.2
- Temp.:
- 22 °C
- pH:
- ca. 2.9
- Type:
- log Pow
- Partition coefficient:
- ca. 0.343
- Temp.:
- 22 °C
- pH:
- ca. 2.9
- Type:
- Pow
- Partition coefficient:
- ca. 0.005
- Temp.:
- 22 °C
- pH:
- ca. 7
- Type:
- log Pow
- Partition coefficient:
- ca. -2.32
- Temp.:
- 22 °C
- pH:
- ca. 7
- Details on results:
- The partition coefficient determined for each sample is shown in Table 1. Mean partition coefficient has been reported: 2.20, log10Pow=0.343. The test material has a predicted dissociation constant of 4.34±0.1. Testing was performed at pH=2.9±0.1 to obtain the test material in its non-ionised form.
Partition coefficient at environmentally relevant pH (pH=7) was calculated using Equation 1. The test material has a corrected coefficient of 4.81×10-3, log10P’ow=-2.32 at pH=7. - Executive summary:
The octanol-water partition coefficient has been determined to be Pow=2.20, log Pow=0.343 at pH=2.9±0.1 and 22°C (study performed at pH=2.9±0.1), and Pow=0.00481, log Pow=-2.32 at pH=7 and 22°C (value calculated), by using the shake-flask method, according to Method A8 Partition Coefficient of Council Regulation (EC) No 440/2008 of 30 May 2008 and Method 107 of the OECD Guidelines for Testing of Chemicals, 27 July 1995.
Reference
Table 1:
sample number |
n-octanol/water volume ratio |
partition coefficient |
log10Pow |
mean partition coefficient |
1 |
1:2 |
2.04 |
0.310 |
2.28 |
2 |
2.53 |
0.403 |
||
3 |
1:1 |
1.98 |
0.297 |
2.07 |
4 |
2.16 |
0.335 |
||
5 |
2:1 |
2.39 |
0.378 |
2.26 |
6 |
2.13 |
0.327 |
Equation 1:
P’ow=Pow/(1+10(pH-pKa))
Where: P’ow= corrected partition coefficient, Pow= estimated partition coefficient, pKa = 4.34, pH = 7.
Description of key information
Octanol-water partition coefficient: Pow=2.20, log Pow=0.343 at pH=2.9±0.1 and 22°C (study performed at pH=2.9±0.1), and Pow=0.00481, log Pow=-2.32 at pH=7 and 22°C (value calculated)
Key value for chemical safety assessment
- Log Kow (Log Pow):
- -2.3
- at the temperature of:
- 22 °C
Additional information
The study performed in experimental laboratory (Fox, 2009, Harlan), dedicated to estimate the partition coefficient of the test material 3-mercaptopropionic acid, has been chosen as a key study. The octanol-water partition coefficient has been determined to be Pow=2.20, log Pow=0.343 at pH=2.9±0.1 and 22°C (study performed at pH=2.9±0.1), and Pow=0.00481, log Pow=-2.32 at pH=7 and 22°C (value calculated), by using the shake-flask method, according to Method A8 Partition Coefficient of Council Regulation (EC) No 440/2008 of 30 May 2008 and Method 107 of the OECD Guidelines for Testing of Chemicals, 27 July 1995.
The other two reported studies (Hansch et al., 1995 and Leo, 1995) are supporting studies. They reported the following values of log Pow: 0.09 and 0.43, respectively. The information given there is not complete (no information about temperature and pH) but qualitatively supports the key study (log Pow<3).
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