Sodium 2-sulphonatoethyl laurate

Partition coefficient

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2012-10-17

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Determination has been run according to standardized method but without GLP compliance.

Principles of method if other than guideline:

The partition coefficient has been determined by dividing the octanol solubility by the aqueous solubility. The logarithm of this value is called the Log POW.

GLP compliance:

no

Type of method:

estimation method (solubility ratio)

Partition coefficient type:

octanol-water

Type:

log Pow

Partition coefficient:

ca. -0.41

Temp.:

20 °C

pH:

7

Details on results:

The octanol solubility is determined of 40 mg/L mixture. The solubility in water is determined to 102 mg/L mixture.
Log POW = Log Octanol solubility (40 mg/L) / Water solubility (102 mg/L)= Log 0.392 = -0.41

Conclusions:

The Log POW of the substance is determined to -0.41.

Executive summary:

The Log POW of the substance is determined to -0.41.

Reference 2

Endpoint:

partition coefficient

Type of information:

(Q)SAR

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The study reports the output from a QSAR prediction model.

Justification for type of information:

QSAR prediction: migrated from IUCLID 5.6

Reason / purpose for cross-reference:

reference to other study

Guideline:

other: REACH guidance on QSARs R.6 May 2008

Principles of method if other than guideline:

The QSAR has been performed in accordance with the OECD principles for QSAR: QSAR derived from the fragment method of Hansch and Leo.

GLP compliance:

not specified

Type of method:

other: QSAR calculation

Partition coefficient type:

octanol-water

Type:

log Pow

Partition coefficient:

ca. 0.6

Remarks on result:

other: The value is derived from a QSAR, no environmental factors are involved.

Table 2 reports the proposed extrapolated values from the measured C8 (-1.56) using this approach.

Table 2

Chain length	KOWWIN	KOWWIN (inc Na+ counter ion)	CLOGP	‘ Measured+extrapolated log Kow
8	0.5966	-1.55	-1.26	-1.56
10	1.5788	-0.57	-0.21	-0.48
12	2.561	0.41	0.85	0.60
14	3.5432	1.40	1.91	1.68
16	4.5254	2.38	2.97	2.76
18	5.5076	3.36	4.02	3.84

Figure 1 illustrates a direct comparison of all the methods.

Figure 1. Comparison of logKow predictions for a series of alkyl isethionates

See the attached document.

A plot of CLOGP predictions against the measured and extrapolated log Kow values (Figure 2) indicates a good agreement between the two methods suggesting that the extrapolated method is a valid approach (see the attached document). Based on this evidencea logKow value of 0.6 is proposed for sodium lauroyl isethionate (CAS 7381-01-3).

Conclusions:

Scientific Validity: ClogP is based on the fragment approach of Hansch and Leo [10] which allows prediction of a homologous series of compounds by increasing the logKow systematically by a value of 0.54 units for every additional carbon.

Applicability: This approach has been shown to be applicable for a range of linear surfactants [7,8, 9,11]. If this approach is applied to this series of alkyl isethionates a value for each homologue can be extrapolated from a measured value for any of the homologues in the series. A plot of CLOGP predictions against the measured and extrapolated log Kow values (Figure 2) indicates a good agreement between the two methods suggesting that the extrapolated method is a valid approach.

Regulatory relevance: A partition coefficient value for the substance under evaluation is a requirement of REACH Annex VII 7.8.

Based on this evidence a logKow value of 0.6 is proposed for sodium lauroyl isethionate (CAS 7381-01-3).

Executive summary:

Scientific Validity: ClogP is based on the fragment approach of Hansch and Leo [10] which allows prediction of a homologous series of compounds by increasing the logKow systematically by a value of 0.54 units for every additional carbon. Applicability: This approach has been shown to be applicable for a range of linear surfactants [7,8, 9,11]. If this approach is applied to this series of alkyl isethionates a value for each homologue can be extrapolated from a measured value for any of the homologues in the series. A plot of CLOGP predictions against the measured and extrapolated log Kow values (Figure 2) indicates a good agreement between the two methods suggesting that the extrapolated method is a valid approach. Regulatory relevance: A partition coefficient value for the substance under evaluation is a requirement of REACH Annex VII 7.8. Based on this evidence a logKow value of 0.6 is proposed for sodium lauroyl isethionate (CAS 7381-01-3).

Reference 3

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

between 10 February 2009 and 02 April 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.

Qualifier:

according to guideline

Guideline:

EU Method A.8 (Partition Coefficient)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Date of inspection: 19/08/08 Date of Signature: 04/03/09

Type of method:

shake-flask method to: flask method

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

Type:

Pow

Partition coefficient:

0.028

Temp.:

22.1 °C

pH:

>= 7.3 - <= 7.5

Type:

log Pow

Partition coefficient:

-1.56

Temp.:

22.1 °C

pH:

>= 7.3 - <= 7.5

Details on results:

Preliminary estimate:
Approximate solubility in n-octanol: <0.124 g/l
Approximate solubility in water: >19.0 g/l
Approximate Pow: <6.51 x 10-3
Log10 Pow: <-2.19

 Definitive test:

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

Organic Phase

Solution	Mean Area
Standard 10.0 mg/l	1.302 x 10^6
Standard 10.2 mg/l	1.376 x 10^6
Organic phase matrix blank	0.000
Sample 1	4.949 x 10^6
Sample 2	4.750 x 10^6
Sample 4	4.492 x 10^6
Sample 5	4.815 x 10^6
Sample 6	4.814 x 10^6

Aqueous Phase

Solution	Mean Area
Standard 251 mg/l	3.263 x 10^7
Standard 257 mg/l	3.404 x 10^7
Aqueous phase matrix blank	0.000
Sample 1	3.405 x 10^7
Sample 2	3.408 x 10^7
Sample 4	3.299 x 10^7
Sample 5	3.432 x 10^7
Sample 6	3.404 x 10^7
Stock solution A	3.492 x 10^7
Stock solution B	3.439 x 10^7

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

Sample Number	Total Weight (mg)*	Organic Phase		Aqueous Phase
		Analysed Concentration (mg/l)	Weight (mg)†	Analysed Concentration (mg/l)	Weight (mg)†	pH
1	87.2	74.7	2.46	2.60 x 10^3	85.6	7.3
2	92.4	71.7	2.51	2.60 x 10^3	90.9	7.3
4	68.7	67.8	3.52	2.51 x 10^3	65.4	7.5
5	116	72.6	1.60	2.62 x 10^3	115	7.4
6	137	72.6	1.89	2.59 x 10^3	135	7.3

pH of n-octanol saturated water:    7.3
pH of stock solution:            7.3
Temperature:                         22.1 ± 0.5°C

*From analysis of the stock solution

†From analysis of the respective phase

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

Sample Number	Organic/Aqueous Volume Ratio	Partition Coefficient	Log10Pow	Mean Partition Coefficient
1	1:1	2.88 x 10^-2	-1.54	2.82 x 10^-2
2		2.76 x 10^-2	-1.56
4	2:1	2.70 x 10^-2	-1.57	2.70 x 10^-2
5	1:2	2.78 x 10^-2	-1.56	2.79 x 10^-2
6		2.80 x 10^-2	-1.55

Mean P_ow : 2.78 x 10^-2        log₁₀P_ow: -1.56        P_owstandard deviation : 6.61 x 10^-4

Validation:

Linearities of the detector response with respect to concentration were assessed over the nominal concentration ranges of 0 to 100 mg/l for the organic phase and 0 to 500 mg/l for the aqueous phase. These were satisfactory with first order correlation coefficients of 1.000 and 0.998 obtained for the organic and aqueous phases respectively.

Discussion:

Substances having a log₁₀P_ow of greater than 3 are regarded as having the potential to bioaccumulate in the environment.

Testing was performed without any pH adjustment to the aqueous phase. Testing by the flask method at neutral pH is the preferred choice for test items that are salts. The pH of the unadjusted n-octanol saturated water and stock solutions were approximately pH 7.

Although sample 3 was abandoned during testing, it was not considered appropriate to repeat the test using a single flask at the required ratio. Results obtained in the definitive test showed consistency between all 5 samples and as such, additional testing would be anticipated to yield no further useful information.

Conclusions:

The partition coefficient of the test item, Sodium Octanoyl Isethionate, has been determined to be 2.78 x 10-2, log10 Pow, -1.56.

Executive summary:

Partition Coefficient:

The partition coefficient of the Sodium Octanoyl Isethionate test item, Sample Number S2952201 has been determined to be 2.78 x 10^-2at 22.1 ± 0.5°C, log₁₀P_ow-1.56, using the shake-flaskthod, Method A8 Partition Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008.

Reference 4

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

08 July 2013 - 06 September 2013

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was performed in accordance with the EC A.8 and OECD 107 guidelines and complied with the principles of GLP.

Qualifier:

according to guideline

Guideline:

EU Method A.8 (Partition Coefficient)

Version / remarks:

(2008)

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)

Version / remarks:

(1995)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 830.7550 (Partition Coefficient, n-octanol / H2O, Shake Flask Method)

Version / remarks:

(1996)

Deviations:

no

GLP compliance:

yes

Type of method:

shake-flask method to: flask method

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

Type:

Pow

Partition coefficient:

2.1

Temp.:

20 °C

pH:

7

Remarks on result:

other: n=6. Standard deviation: 1.1.

Type:

log Pow

Partition coefficient:

0.3

Temp.:

20 °C

pH:

7

Details on results:

The log Pow values were within the criterion range of ± 0.3 log units (see table below). Based on this, the Pow and log Pow of the test substance are given as the mean value of all measurements.

Results Shake-flask method

 

Ratio n-octanol : water [v:v]	Analysed concentration		Pow		log Pow	pH
	n-octanol [g/L]	water [g/L]	Individual	Mean
1:1	1.29x10-3	6.33x10-4	2.0	2.1	0.3	7.1
	1.35x10-3	6.15x10-4	2.2		0.3	7.1
1:2	1.37x10-3	8.04x10-4	1.7	1.4	0.2	7.1
	1.02x10-3	8.60x10-4	1.2		0.1	7.1
2:1	1.29x10-3	7.60x10-5	17^1	3.5	1.2	7.1
	1.11x10-3	3.16x10-4	3.5		0.5	7.1

 

¹ This value is an outlier, therefore not used to calculate the mean Pow and mean log Pow.

 

A small test substance was detected in the pretreated samples from the blank mixture which was considered to have no effect on the study.

Conclusions:

The log Pow of the substance at pH 7 and 20°C has been determined as 0.3 (Pow of 2.1) using the shake-flask method with modification to stirred flasks (GLP-compliant study in accordance with EC A.8, OECD 107 and EPA OPPTS 830.7550).

Description of key information

Given the technical complications to experimentally determine log Kow values for surface active substances, a weight of evidence approach has been taken to generate a relevant logKow value to include current experimental values combined with supporting predictive and QSAR approaches based upon ClogP.

Key value for chemical safety assessment

Log Kow (Log Pow):

0.6

at the temperature of:

22 °C

Additional information

Refer to the Annex of the Chemical Safety Report: Appendix 1: Justification in support of read-across for sodium 2 -sulphonatoethyl laurate for further discussion and information on the scientific validity, applicability and regulatory relevance.