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Partition coefficient

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Endpoint:
partition coefficient
Type of information:
other: experimental study on hydrolysis product Boric acid
Adequacy of study:
key study
Study period:
No data
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
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).

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 %.

Conclusions:
The log partition coefficient n-octanol/water (Log Pow) of the test substance appeared to be -1.09 ± 0.16 (22 ± 1 ºC).
Endpoint:
partition coefficient
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
justification for analogue approach: see IUCLID section 13 "Read-across justification"
Reason / purpose for cross-reference:
read-across source
Type:
log Pow
Partition coefficient:
0.785
Temp.:
25 °C
Remarks on result:
other: pH unknown
Details on results:
The reported octanol/water partition coefficient is an average of at least three measurements.
The experimental uncertainties in the Kow determination are around 1.0%.
Conclusions:
log Pow = 0.785
Executive summary:

According to a reliable publication (Tewari Y.B. et al, 1982), the Log Pow of Tributyl borate is 0.785 (at 25°C). The measurement was performed with a modified Generator Column Method.

Description of key information

Study scientifically not necessary because Tributyl borate is rapidly hydrolyzed to Boric acid and n-Butanol in the presence of water:

- log partition coefficient n-octanol/water (Log Pow) of Boric acid: -1.09 ± 0.16 (at 22 ± 1 ºC and pH 7.5);

- log partition coefficient n-octanol/water (Log Pow) of n-Butanol: 0.785 (at 25 ºC).

Key value for chemical safety assessment

Log Kow (Log Pow):
1
at the temperature of:
25 °C

Additional information