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EC number: 203-016-8 | CAS number: 102-24-9
Partition coefficient
Administrative data
Link to relevant study record(s)
- Endpoint:
- partition coefficient
- Type of information:
- experimental study
- Adequacy of study:
- weight of evidence
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- data from handbook or collection of data
- Guideline:
- other: no data
- Principles of method if other than guideline:
- no data
- GLP compliance:
- not specified
- Type of method:
- other: measured
- Partition coefficient type:
- octanol-water
- Analytical method:
- not specified
- Type:
- log Pow
- Partition coefficient:
- -0.77
- Remarks on result:
- other: value from secondary literature source
- Details on results:
- The log Pow value has been obtained from a secondary literature source which did not list the temperature or pH of the test system.
- Conclusions:
- The value for the log Pow of Methanol is reported to be -0.77 from a reliable peer-reviewed handbook source.
- Endpoint:
- partition coefficient
- Type of information:
- experimental study
- Adequacy of study:
- weight of evidence
- Study period:
- No data
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: GLP guideline study
- Qualifier:
- according to guideline
- Guideline:
- EU Method A.8 (Partition Coefficient)
- Deviations:
- not specified
- GLP compliance:
- yes
- Type of method:
- HPLC method
- Partition coefficient type:
- octanol-water
- Analytical method:
- high-performance liquid chromatography
- Type:
- log Pow
- Partition coefficient:
- -1.09
- Temp.:
- 22 °C
- pH:
- 7.5
- Details on results:
- Preliminary estimate: The estimated n-octanol solubility was approximately 18.08 g/L. The water solubility of the substance in water was 49.23 g/L. Therefore the Pow, estimate = 18.08/49.23 = 0.37 or log Pow,estimated = -0.43.
The log Pow of the test substance was -1.09 ± 0.16 (22 ± 1 ºC). - Conclusions:
- The log partition coefficient n-octanol/water (Log Pow) of boric acid appeared to be -1.09 ± 0.16 (22 ± 1 ºC).
Referenceopen allclose all
Value from generally accepted authoritative secondary source. No data available for temperature and pH value.
All concentrations of the n-octanol phases are corrected with the recovery of the extraction, as shown in the tables below.
Results of the partition test:
Serie |
Conc. n-octanol phase (g/L) |
Conc. aqueous phase (g/L) |
Pow |
Log Pow |
Mean log Pow |
1 |
0.030 |
0.513 (pH 7.5) |
0.06 |
-1.23 |
-127 |
0.025 |
0.519 (pH 7.5) |
0.05 |
-1.32 |
||
2 |
0.016 |
0.304 (pH 7.5) |
0.05 |
-1.27 |
-1.09 |
0.033 |
0.302 (pH 7.5) |
0.11 |
-0.97 |
||
3 |
0.063 |
0.579 (pH 7.5) |
0.11 |
-0.96 |
-0.97 |
0.059 |
0.548 (pH 7.5) |
0.11 |
-0.97 |
Mean value of all determinations: Series 1, 2 and 3:
Pow= 0.081 ± 0.030
Log Pow= -1.09 ± 0.16 (22 ± 1ºC)
The recovery of the partition test is calculated with the concentrations of the stock solution which was analysed by means of HPLC.
Determination of the recovery:
est |
n-octanol phase (mg/L) |
Aqueous phase (mg) |
Total (mg) |
Recovery (%) |
1 |
0.829 |
15.477 |
16.306 |
93 |
2 |
0.743 |
9.089 |
9.823 |
112 |
3 |
1.832 |
33.820 |
35.651 |
102 |
Results of the recovery test after extraction with 0.01 N H2SO4:
Original concentration (g/L) |
Concentration after extraction (g/L) |
Recovery % |
0.069 |
0.054 |
78 |
0.069 |
0.046 |
66 |
The mean value of the recovery of the two solutions is 72 ± 8 %.
Description of key information
TMBX is hydrolytically unstable and experimental derivation of a octanol water partition coefficient is technically not possible. A value of -5.67 is predicted by KOWWIN v1.68 however given the hydrolytic instability of the substance this cannot be considered reliable. TMBX hydrolyses to form methanol and boric acid, both of which are toxicologically significant species and the partition coefficients for these breakdown products should be considered instead. The log partition coefficient n-octanol/water (Log Pow) of boric acid was measured to be -1.09 ± 0.16 (22 ± 1 ºC). The value for the log Pow of Methanol is reported to be -0.77 from a reliable peer-reviewed handbook source.
Based upon the most sensitive environmental toxicity studies available, the partition coefficient for Boric acid was selected as the most appropriate value for the Chemical Safety Assessment.
Key value for chemical safety assessment
- Log Kow (Log Pow):
- -1.09
- at the temperature of:
- 22 °C
Additional information
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