Sodium naphthalene-2-carboxylate

Partition coefficient

Administrative data

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Testing was conducted between 16 May 2008 and 13 June 2008.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study conducted to GLP and in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not effect the quality of the relevant results.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2008

Report date:

2008

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

EU Method A.8 (Partition Coefficient)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

The work described was performed in compliance with UK GLP standards (Schedule 1, Good Laboratory Practice Regulations 1999 (SI 1999/3106 as amended by SI 2004/0994)).

Type of method:

shake-flask method to: flask method

Partition coefficient type:

octanol-water

Test material

Test material information

Constituent 1

Reference substance name:

Sodium naphthalene-2-carboxylate

EC Number:

700-038-4

Cas Number:

17273-79-9

Molecular formula:

C11 H7 Na O2

IUPAC Name:

Sodium naphthalene-2-carboxylate

Study design

Analytical method:

photometric method

Results and discussion

Partition coefficient

Type:

log Pow

Partition coefficient:

-1.49

Temp.:

22.2 °C

pH:

ca. 7

Any other information on results incl. tables

Preliminary estimate

Approximate solubility in n-octanol: 7.4 x 10^-2 g/l
Approximate solubility in water:       > 26.2 g/l
Approximate P_ow:   2.82 x 10^-3
Log₁₀ P_ow:   -2.55

               Definitive test

The absorbances obtained for the standard, stock and sample solutions are shown in the following two tables:

Organic Phase

Solution	Absorbance
Standard 26.3 mg/l	0.48243
Standard 25.4 mg/l	0.49886
Organic phase matrix blank	None detected
Sample 1	0.30913
Sample 2	0.30069
Sample 3	0.36801
Sample 4	0.33432
Sample 5	0.43799
Sample 6	0.39313

Aqueous Phase

Solution	Absorbance
Standard 26.3 mg/l	0.51781
Standard 25.4 mg/l	0.58801
Aqueous phase matrix blank	None detected
Sample 1	0.50465
Sample 2	0.49188
Sample 3	0.49135
Sample 4	0.49643
Sample 5	0.50327
Sample 6	0.50906
Stock solution A	0.50507
Stock solution B	0.51063

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

Sample Number	Volume of water saturated n-octanol (ml)	Volume of stock solution (ml)	Total Weight (mg)*	Organic Phase		Aqueous Phase
				Analysed Concentration (mg/l)	Weight (mg)†	Analysed Concentration (mg/l)	Weight (mg)†	pH
1	120	30	35.6	32.6	3.91	1.18 x 10^3	35.4	8.0
2	120	30	35.6	31.7	3.80	1.15 x 10^3	34.5	8.3
3	100	50	59.3	38.8	3.88	1.15 x 10^3	57.4	8.5
4	96	48	57.0	35.2	3.38	1.16 x 10^3	55.7	8.5
5	65	65	77.1	46.2	3.00	1.18 x 10^3	76.4	8.2
6	70	70	83.1	41.4	2.90	1.19 x 10^3	83.3	8.5

* From analysis of the stock solution

† From analysis of the respective phase

pH of n-octanol saturated water:           7.7
pH of stock solution:                             7.9
Temperature:                                        22.2 ± 0.5°C

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

Sample Number	n-Octanol/Water Volume Ratio	Partition Coefficient	Log10 Pow	Mean Partition Coefficient
1	4:1	2.76 x 10^-2	-1.56	2.76 x 10^-2
2		2.76 x 10^-2	-1.56
3	2:1	3.38 x 10^-2	-1.47	3.21x 10^-2
4		3.04 x 10^-2	-1.52
5	1:1	3.93 x 10^-2	-1.41	3.71 x 10^-2
6		3.48 x 10^-2	-1.46

Mean P_ow  : 3.23 x 10^-2 log₁₀ P_ow : -1.49                        P_ow standard deviation : 4.58 x 10^-3

  Validation

Linearities of the detector response with respect to concentration were assessed over the nominal concentration range of 0 to 50 mg/l, for both the organic phase and the aqueous phase. These were found to be satisfactory, with a correlation coefficient of 1.00 being obtained for both phases.

Discussion

Substances having a log₁₀ P_owof greater than 3 are regarded as having the potential to bioaccumulate in the environment.

The test was carried out using unadjusted n-octanol saturated water, at ~ pH 7 (as recommended for salts).

Conclusion

The partition coefficient of the test material has been determined to be 3.23 x 10^-2 at 22.2 ± 0.5°C, log₁₀P_ow -1.49.

Applicant's summary and conclusion

Conclusions:

The partition coefficient of the test material has been determined to be 3.23 x 10-2 at 22.2 ± 0.5°C, log10 Pow -1.49

Executive summary:

For substance Na-Na in project number 1307 - 0436 the determination was carried out using the shake-flask method, Method A8 of Commission Directive 92/69/EEC (which constitutes Annex V of Council Directive 67/548/EEC). The partition coefficient of the test material has been determined to be 3.23 x 10-2 at 22.2 ± 0.5°C, log10 Pow -1.49.