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Partition coefficient

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Reference
Endpoint:
partition coefficient
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
February from 4th to 6th, 1992
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail
Remarks:
Although the log Kow value resulted outside of the applicability domain for the shake-flask method, the test result can be considered as reliable and representative for the tested substance.
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH
The usage of information on Direct Blue 199_Na, which has the same main component and with a different counter ion, can be considered as suitable and appropriated because the difference in salification is expected to not influence the characteristics related to the specific end-point.
The impurity profile does not impact on the read across proposed. Details on the approach followed are included in the document attached to the IUCLID section 13.
Reason / purpose:
read-across source
Qualifier:
according to
Guideline:
OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)
Qualifier:
according to
Guideline:
EU Method A.8 (Partition Coefficient)
GLP compliance:
yes
Type of method:
shake-flask method to: flask method
Partition coefficient type:
octanol-water
Analytical method:
photometric method
Type:
log Pow
Partition coefficient:
-2.29
Temp.:
25 °C
pH:
4.2
Remarks on result:
other: range: -2.15 -2.51
Type:
Pow
Partition coefficient:
0.005
Temp.:
25 °C
pH:
4.2
Remarks on result:
other: SD: 0.0020
Details on results:
REFERENCE COMPOUNDS
The values found agree well with either the OECD-value
- Trichloroethylene: guideline logP of 2.54 - 2.76
- o-Dichlorobenzene: guideline logP of 3.36
- Dibutylphthalate: guideline logP of 4.48 - 4.22

Volume ratios Vaqu/Vorg
V1 V2 = 1/2* V1 V3 = 2* V1
Exp. N. 1.1 1.2 2.1 2.2 3.1 3.2
Volume in aqu. Phase [ml] 3 3 2 2 4 4
Volume in oct. phase [ml] 3 3 4 4 2 2
Conc. in aqu. phase before shaking [E-4 Mol/l] 2.713 2.713 2.713 2.713 2.713 2.713
Conc. in oct. phase after equilibrium [E-4 Mol/l] 0.014 0.013 0.008 0.008 0.020 0.019
Conc. in aqu. phase after equilibrium [E-4 Mol/l] 2.692 2.662 2.672 2.640 2.652 2.651
Partition coefficient Pow 0.0052 0.0048 0.0028 0.0029 0.0074 0.0073
Mean Pow's for each volume ratio 0.005 0.0029 0.0074
pH of aqu. phase after equilibrium 4.4 4.42 4.24 4.25 4.06 4.12
Mass balance
Stocck solution 6.782 mg 25 ml water
g(o) = weight-in [mg] 0.814 0.814 0.543 0.543 1.085 1.085
g(w) = weight-out in aqu. phase [mg] 0.808 0.799 0.534 0.528 1.061 1.060
g(or) = weight-out in oct. phase [mg] 0.004 0.004 0.003 0.003 0.004 0.004
total mass weight-out [mg] 0.812 0.802 0.538 0.531 1.065 1.064
Conclusions:
log Pow: - 2.29 at 25 °C and pH 4.2
Executive summary:

The substance was tested for partition coefficient according to the OECD guideline 107 and EU Method A.8, by the shake flask procedure. The concentration of the test substance in the water/octanol phases was determined spectrophotornetrically. For the first run, a volume ratio of n-octanol to water and a quantity of substance was chosen. For the second run, the originally chosen volume ratio was divided by two, and, for a third run, it was multiplied by two; duplicate vessels were used in all three runs. The complete experimental equipment and procedures were tested by determining the partition coefficients of three reference compounds listed in the test guideline (i.e. Trichloroethylene, o-Dichlorobenzene and Dibutylphthalate) and the values recorded agree well with either the guideline-value.

Partition Coefficient between n-Octanol and aqueous phase was stated at 0.0051 at 25 °C and pH 4.2 (log Pow: -2.29).

Conclusion

log Pow: - 2.29 at 25 °C and pH 4.2 (Pow: 0.0051)

Description of key information

- 2.29 at 25 °C and pH 4.2 (Pow: 0.0051)

Key value for chemical safety assessment

Log Kow (Log Pow):
-2.29
at the temperature of:
25 °C

Additional information

Shake-flask method - OECD guideline 107