Registration Dossier

Administrative data

Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
08 January 2009 to 07 February 2009
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of relevant results.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2009
Report Date:
2009

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
EU Method A.8 (Partition Coefficient)
Deviations:
not specified
GLP compliance:
yes (incl. certificate)
Remarks:
Date of inspection: 19 August 2008; Date of signature: 04 March 2009
Type of method:
shake-flask method to: flask method
Partition coefficient type:
octanol-water

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Sponsor's identification : H-CB sodium salt
Description : blue solid
Purity : 94.8%
Lot number : MB-2
Date received : 04 December 2008
Storage conditions : room temperature in the dark

Study design

Analytical method:
high-performance liquid chromatography

Results and discussion

Partition coefficientopen allclose all
Type:
log Pow
Partition coefficient:
<= -3.59
Temp.:
21.5 °C
pH:
>= 7 - <= 7.2
Type:
Pow
Partition coefficient:
<= 0
Temp.:
21.5 °C
pH:
>= 7 - <= 7.2

Any other information on results incl. tables

Result

Preliminary estimate

Solubilityin n-octanol:                     ≤ 1.35 x 10-2g/l
Solubility in water:                           ≥ 20.0 g/l
Approximate Pow:                             ≤ 6.74 x 10-4
Log10Pow:                                                    ≤ -3.17

Definitive test

The mean peak areas or heights obtained for the standard, stock and sample solutions are shown in the following two tables:

Table 2– Aqueous Phase

Solution

MeanArea

Standard 259 mg/l

3.652 x 103

Standard 262 mg/l

3.647 x 103

Sample 1

3.721 x 103

Sample 2

3.722 x 103

Sample 3

3.919 x 103

Sample 4

3.880 x 103

Sample 5

3.959 x 103

Sample 6

4.000 x 103

Stock solution A

3.453 x 103

Stock solution B

3.507 x 103

Table 3– Organic Phase

Solution

MeanHeight*

Standard 10.4 mg/l

9.536

Standard 10.5 mg/l

9.537

Sample 1

≤ 1.26

Sample 2

≤ 1.26

Sample 3

≤ 1.26

Sample 4

≤ 1.26

Sample 5

≤ 1.26

Sample 6

≤ 1.26

*see section below for discussion on use of peak heights.

The total weights (mg) and analysed concentration (mg/l) of the respective phases are shown in the following table:

Table 4

Sample Number

Total Weight (mg)*

Organic Phase

Aqueous Phase

Analysed Concentration (mg/l)

Weight (mg)†

Analysed Concentration (mg/l)

Weight (mg)†

pH

1

273

≤0.275

≤1.51 x 10-2

1.06 x 103

292

7.0

2

447

≤0.275

≤2.48 x 10-2

1.06 x 103

478

7.0

3

348

≤0.275

≤9.63 x 10-3

1.12 x 103

391

7.1

4

348

≤0.275

≤9.63 x 10-3

1.11 x 103

388

7.0

5

516

≤0.275

≤7.16 x 10-3

1.13 x 103

588

7.1

6

358

≤0.275

≤4.95 x 10-3

1.14 x 103

411

7.2

*From analysis of the stock solution

†From analysis of the respective phase

pH of n-octanol saturated water:    4.7                  
pH of stock solution:            6.9
Temperature:                        21.5 ± 0.5°C

The partition coefficient determined for each sample is shown in the following table:

Table 5

Sample Number

Organic/Aqueous Volume Ratio

Partition Coefficient

Log10Pow

Mean Partition Coefficient

1

5:1

≤2.59 x 10-4

≤-3.59

≤2.59 x 10-4

2

≤2.59 x 10-4

≤-3.59

3

10:1

≤2.46 x 10-4

≤-3.61

≤2.47 x 10-4

4

≤2.49 x 10-4

≤-3.61

5

20:1

≤2.44 x 10-4

≤-3.61

≤2.42 x 10-4

6

≤2.41 x 10-4

≤-3.62

Overall Pow :≤2.59 x 10-4              log10Pow:≤-3.59    

 

 Validation

The linearity of the detector response with respect to concentration was assessed over the nominal concentration range of 0 to 500 mg/l. This was satisfactory with a correlation coefficient of 1.000 being obtained.

Discussion

The test material contained sulphonic acid sodium salt groups and therefore pKa values outside the environmentally relevant pH range for the determination of partition coefficient. As a result, testing was performed at pH 7 using the shake-flask method as recommended for salts.

An organic matrix blank chromatogram was subtracted from the organic standards and samples to remove the baseline drift due to the mobile phase gradient. This was not performed for the aqueous standards and samples as the drift was not significant compared to the size of the test material peaks.

As no definable peak was detectable in the organic phase samples chromatography, a 4 x baseline noise was calculated around the retention time of the test material as a worse case scenario and used as a less than or equal to value to represent peak height.

Applicant's summary and conclusion

Conclusions:
The partition coefficient of the test material has been determined to be ≤ 2.59 x 10-4, log10 Pow, ≤ -3.59.
Executive summary:

Partition Coefficient. Less than or equal to 2.59 x 10-4 at 21.5 ± 0.5°C, log10 Pow,≤ ‑3.59, using the shake-flask method, Method A8 Partition Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008.