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EC number: 601-779-5 | CAS number: 121451-02-3
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:
- 29 June 2000 - 21 August 2000
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Remarks:
- Study conducted in compliance with agreed protocols, with no or minor deviations from the standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results. The study report was conclusive, done to valid guidelines and conducted under GLP conditions.
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)
- Deviations:
- no
- 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:
- shake-flask method to: flask method
- Partition coefficient type:
- octanol-water
- Analytical method:
- high-performance liquid chromatography
- Key result
- Type:
- log Pow
- Partition coefficient:
- 4.94
- Temp.:
- 20 °C
- pH:
- 6.77 - 7.95
- Remarks on result:
- other: Standard deviation 0.288 (Temp. ± 1 °C)
- Details on results:
- Preliminary Test:
Octanol and aqueous phases were at equilibrium after 24 hours.
The approximate logPow was 5.58 and the 2:77.3 ratio of octanol to water was sufficient to quantitate the amount of test material in both phases.
The average percent recovery was 98.6 % for both the pre and post dosing spikes.
Calculation of the total amount of test material in both phase against the known amount of test material in the standard spikes, showed recoveries for the 2, 4, 22, and 24 hour sampling times of 99.6, 98.2, 99.6 and 99.1 %, respectively.
Method Validation:
- Octanol Phase Samples
Mean test material recoveries determined by HPLC analyses at concentrations of 0.75 and 1.7 mg/mL (nominal), averaged 106.5 ± 0.77 % and 106.7 ± 0.78 %, respectively.
- Aqueous Phase Samples
Mean percent recovery for the low and high aqueous dose spike was 96.3 and 101.6 %. Mean test material recoveries determined by HPLC analyses of the water samples at concentrations of 1.99 and 19.9 ng/mL, averaged 88.9 ± 3.06 % and 96.4 ± 3.42 %, respectively.
Both methods were successfully validated at the concentration ranges expected in the definitive test.
Definitive Test:
Results can be seen in Table 1. - Conclusions:
- Under the conditions of the test, the n-octanol/water partition coefficient was determined to be logPow 4.94 (absolute standard deviation 0.288) at 20 ± 1 °C using the shake flask method.
- Executive summary:
The n-octanol/water partition coefficient of the test material was determined in a GLP study which was performed in accordance with the standardised guidelines OECD 107 and EPA OPPTS 830.7550 using the shake flask method with HPLC analysis.
The study was conducted in three phases: preliminary test, method validation test and definitive test. The definitive test was conducted at a concentration of 1.54 mg/mL in three different volume ratios of octanol to water (1:77.3, 2:77.3, and 3:77.3). All three tests were prepared in duplicate. The test solutions were equilibrated at 20 ± 1°C by shaking over a 24 hour period. The octanol and water phases were separated by centrifugation at 4500 rpm for 30 minutes at 20 °C. An aliquot from each octanol phase replicate was removed and diluted. An exact volume of each aqueous phase was extracted with dichloromethane, and concentrated for analysis. All samples were analyzed by HPLC to determine the concentrations of test material.
The partition coefficient (Pow) was calculated as the ratio of the concentration of test material in the octanol phase to that in the aqueous phase for all three volume test ratios of octanol to water. Under the conditions of this experiment the overall mean Pow for the three volume ratios was 86200 ± 57200. The mean log Pow was 4.94 with an absolute standard deviation of 0.288.
Reference
Table 1: Octanol/Water Partition Coefficient
Phase |
Volume Ratio |
Replicate |
Corrected HPLC Concentration (µg/mL) |
Molarity (M) |
Partition Coefficient (Pow) |
LogPow |
Mean Pow ± SD |
Mean LogPow |
Absolute SD of Mean LogPow |
Oct. |
1:77.3 |
1 |
1554.741 |
2.94 E-03 |
25384 |
4.40 |
8.62 E04 ± 5.72 E04 |
4.94 |
0.288 |
Aq. |
1:77.3 |
1 |
0.06125 |
1.16 E-07 |
|||||
Oct. |
1:77.3 |
2 |
1555.591 |
2.94 E-03 |
25092 |
4.40 |
|||
Aq. |
1:77.3 |
2 |
0.06200 |
1.17 E-07 |
|||||
Oct. |
2:77.3 |
1 |
1550.778 |
2.91 E-03 |
140660 |
5.15 |
|||
Aq. |
2:77.3 |
1 |
0.01103 |
2.08 E-08 |
|||||
Oct. |
2:77.3 |
2 |
1541.867 |
2.91 E-03 |
160277 |
5.20 |
|||
Aq. |
2:77.3 |
2 |
0.00962 |
1.82 E-08 |
|||||
Oct. |
4:77.3 |
1 |
1545.079 |
2.92 E-03 |
67559 |
4.83 |
|||
Aq. |
4:77.3 |
1 |
0.02287 |
4.32 E-08 |
|||||
Oct. |
4:77.3 |
2 |
1531.335 |
2.89 E-03 |
98510 |
4.99 |
|||
Aq. |
4:77.3 |
2 |
0.0155 |
2.94 E-08 |
Oct. = Octanol
Aq. = aqueous
Description of key information
LogPow 4.94 at 20 °C, shake flask method, HPLC, OECD 107, EPA OPPTS 830.7550, Sarff 2000.
Key value for chemical safety assessment
- Log Kow (Log Pow):
- 4.94
- at the temperature of:
- 20 °C
Additional information
The n-octanol/water partition coefficient of the test material was determined in a GLP study which was performed in accordance with the standardised guidelines OECD 107 and EPA OPPTS 830.7550 using the shake flask method with HPLC analysis. The study was assigned a reliability score of 1, reliable without restrictions, in line with the principles of Klimisch et al. (1997).
The study was conducted in three phases: preliminary test, method validation test and definitive test. The definitive test was conducted at a concentration of 1.54 mg/mL in three different volume ratios of octanol to water (1:77.3, 2:77.3, and 3:77.3). All three tests were prepared in duplicate. The test solutions were equilibrated at 20 ± 1 °C by shaking over a 24 hour period. The octanol and water phases were separated by centrifugation at 4500 rpm for 30 minutes at 20 °C. An aliquot from each octanol phase replicate was removed and diluted. An exact volume of each aqueous phase was extracted with dichloromethane, and concentrated for analysis. All samples were analyzed by HPLC to determine the concentrations of test material.
The partition coefficient (Pow) was calculated as the ratio of the concentration of test material in the octanol phase to that in the aqueous phase for all three volume test ratios of octanol to water. Under the conditions of this experiment the overall mean Pow for the three volume ratios was 86200 ± 57200. The mean log Pow was 4.94 with an absolute standard deviation of 0.288.
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