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Partition coefficient

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Reference
Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)
Version / remarks:
13 April 2004
Deviations:
no
Qualifier:
according to guideline
Guideline:
other: Commission Regulation (EU) 2016/266 adopted 7 December 2015, Method A.24 “Partition Coefficient (N-OCTANOL/WATER), HIGH PERFORMANCELIQUID CHROMATOGRAPHY (HPLC) METHOD.
Version / remarks:
7 December 2015
Deviations:
no
GLP compliance:
no
Other quality assurance:
ISO/IEC 17025 (General requirements for the competence of testing and calibration laboratories)
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Specific details on test material used for the study:
Name sodium 3-sulfobenzoate
Batch no. 170103
Appearance White crystalline powder
Composition Sodium 3-Sulfobenzoate
CAS No. 17625-03-5
EINECS-No. 241-602-5
Molecular formula C7H5SO5Na
Molecular weight 224.17 g/mol
Purity > 99.0% (Titration with NaOH, Glass indicating electrode, Calomel reference electrode)
Homogeneity totally homogeneous
Vapour pressure n.a.
Stability H2O: 96 h; EtOH: unknown; acetone: unknown; CH3CN: unknown; DMSO: unknown
Solubility H2O: >1 g/l; EtOH: unknown; acetone: unknown; CH3CN: unknown; DMSO: unknown
Production date Year 2017
Expiry date 14. Feb. 2019
Storage Room Temperature (20 ± 5°C), keep away from humidity
Analytical method:
high-performance liquid chromatography
Type:
log Pow
Remarks on result:
not determinable because of methodological limitations
Remarks:
LogPow is not calculable, because K is negative. The retention time of the peak of the test substance is lower than the retention time of thiourea, which was used for the determination of the dead time of the method.
Details on results:
The correlation log K / log POW was used for the calculation of the log POW of the components of test substance sodium 3-sulfobenzoate. Due to the fact that the retention time of the peak lay below the retention time of thiourea (log POW is not calculable), the log POW of these peaks is stated as < 0.3.

Reference Substances

Measurement Data

The retention times which were recorded for the reference substances are presented in the following table.

Table. Retention Times (RT) of the Reference Substances.

Compound

RT 1

RT 2

RT 3

RT 4

RT 5

RT 6

 

min.

min.

min.

min.

min.

min.

Thiourea

1.393

1.393

1.393

1.393

1.393

1.393

2-Butanone

1.860

1.860

1.860

1.860

1.860

1.860

Benzyl alcohol

2.250

2.250

2.250

2.250

2.253

2.253

Acetophenone

2.803

2.807

2.807

2.807

2.807

2.807

Nitrobenzene

3.353

3.360

3.360

3.360

3.360

3.363

Benzene

4.790

4.797

4.793

4.797

4.797

4.800

Toluene

7.667

7.680

7.677

7.680

7.680

7.687

Naphthalene

10.837

10.860

10.853

10.860

10.853

10.867

 

Calculated Values

For each reference substance, the calculated capacity factors are presented in the following table.

Table. Capacity factors Reference Substances.

Compound


Retention Time

Mean

Retention Time
Standard
 Deviation

Retention Time
Relative
Standard Deviation

k

 

min.

min.

%

 

Thiourea

1.393

0.000

0.000

0.0000

2-Butanone

1.860

0.000

0.000

0.3349

Benzyl alcohol

2.251

0.002

0.076

0.6156

Acetophenone

2.806

0.001

0.048

1.0140

Nitrobenzene

3.359

0.003

0.098

1.4111

Benzene

4.796

0.003

0.072

2.4418

Toluene

7.678

0.007

0.086

4.5108

Naphthalene

10.855

0.010

0.095

6.7907

 


Log POW/ log k

The values for log k and log POWof the reference substances are presented in the following table.

Table. Log k and log POW of Reference Substances.

Compound

log k

log POW

2-Butanone

-0.4750

0.30

Benzyl alcohol

-0.2107

1.10

Acetophenone

0.0060

1.70

Nitrobenzene

0.1496

1.90

Benzene

0.3877

2.10

Toluene

0.6543

2.70

Naphthalene

0.8319

3.60

 

Graph

Correlation Results

Dead time is 1.393 ± 0.000 minutes, with RSD (relative standard deviation) 0.0%. 

The RSD of the retention times of the reference substances lay all below 0.1 %.

 

Equation of the regression:

log k = 0.4294 * log POW– 0.63
with a coefficient of determination r2= 0.9619

 

Test Substance sodium 3-sulfobenzoate

Measurement Data

The retention times of the test substance are presented in the following table.

Table. Retention Times (RT) Test Substance

Measurement

RT

 

min.

Measurement 1

0.920

Measurement 2

0.937

Measurement 3

0.943

Mean

0.933

Standard deviation

0.012

 

Calculated Values

The calculated values are presented in the following table.

Table. Capacity Factor, log Capacity Factor, log POWTest Substance.

Measurement

k

log k

log POW

Measurement 1

-0.3397

n.c.*

n.c.*

Measurement 2

-0.3278

n.c.*

n.c.*

Measurement 3

-0.3230

n.c.*

n.c.*

Mean

 

 

n.c.*

Relative Standard deviation

 

 

n.c.*

*Not calculable, because K is negative. The retention time of the peak is lower than the retention time of thiourea, which was used for the determination of the dead time of the method.

 

log POWwas calculated from the capacity factor as follows:

 

log POW= (log k + 0.63) / 0.4294

 

Result and Validity

Result

The correlation log K / log POWwas used for the calculation of the log POWof the components of test substancesodium 3-sulfobenzoate. Due to the fact that the retention time of the peaklay below the retention time of thiourea(log POWis not calculable), the log POWof these peaks is stated as < 0.3.


Validity

The validity criteria and results are presented in the following table.

Table. Validity Criteria and Results.

Peak

Parameter

Criterion

Found

Assessment

1

Range (Max – Min. log POW)

< 0.1

n.c.*

n.c.*

Value within Range of Reference Substances

0.30 – 3.60

n.c.*

n.c.*

*Not calculable, because K is negative. The retention time of peak 1 is lower than the retention time of thiourea, which was used for the determination of the dead time of the method.

Conclusions:
Variations in the retention times of reference substances and test substance are very small. Therefore a stable configuration of the HPLC-column can be assumed.
The correlation log K / Log POW is acceptable: the coefficient of determination r2 was calculated with 0.9619. This value was considered as sufficiently high to use the calibration function for the determination of the log POW of test substances.
However, the log POW of the test substance sodium 3-sulfobenzoate was not calculable, because the retention time lay below the retention time of the dead time marker thiourea, resulting in a negative capacity factor K.
A retention time shorter than the dead time is an indicator for charged molecules which are repelled from the HPLC column particles and therefore have access to less effective column volume. As the test substance is a strong acid, a fully protonated species cannot be tested and; therefore, the log POW of sodium 3-sulfobenzoate is stated as < 0.3.
Executive summary:

The determination of the log POW of sodium 3-sulfobenzoate has been performed using the HPLC method according to OECD 117 resp. EU A.24. The study was performed using a HPLC with a C18 column. Seven reference substances with different retention times and thiourea for the determination of the dead time were used to produce a calibration curve, since retention time on hydrophobic columns and POW are

correlated. The reference substances were chosen based on the results of the pre-test.

One vial was filled with the reference substance mix and one vial with the test substance solution. The vials were analysed using the HPLC. First one injection from the solvent blank methanol/water 65/35 (v/v) was made. Then three injections were measured from the reference substance mix, three injections from the test substance and again three injections from the reference substance mix.

For each reference substance, the capacity factor k was calculated from the retention time of thiourea and the retention time of the respective reference substance.

A calibration function (log k versus log POW, linear fit) was determined using the literature values for POW of the reference substances and the retention times in the six determinations.

The chromatogram of the test substance gave one major peak. The log POW of the peak was not calculable, because the retention time lay below the retention time of thiourea.

The log POW of sodium 3 -sulfobenzoate is stated as < 0.3.

Description of key information

The determination of the log POWof sodium 3-sulfobenzoate has been performed using the HPLC method according to OECD 117 resp. EU A.24. The study was performed using a HPLC with a C18 column. Seven reference substances with different retention times and thiourea for the determination of the dead time were used to produce a calibration curve, since retention time on hydrophobic columns and POWare

correlated. The reference substances were chosen based on the results of the pre-test.

One vial was filled with the reference substance mix and one vial with the test substance solution. The vials were analysed using the HPLC. First one injection from the solvent blank methanol/water 65/35 (v/v) was made. Then three injections were measured from the reference substance mix, three injections from the test substance and again three injections from the reference substance mix.

For each reference substance, the capacity factor k was calculated from the retention time of thiourea and the retention time of the respective reference substance.

A calibration function (log k versus log POW, linear fit) was determined using the literature values for POWof the reference substances and the retention times in the six determinations.

The chromatogram of the test substance gave one major peak. The log POWof the peak was not calculable, because the retention time lay below the retention time of thiourea.

The log POWof sodium 3 -sulfobenzoate is stated as < 0.3.

Key value for chemical safety assessment

Log Kow (Log Pow):
0.3
at the temperature of:
25 °C

Additional information

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