Sodium 2-sulphonatoethyl laurate

Additional physico-chemical information

Administrative data

Endpoint:

other: Critical micelle concentration (CMC)

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

16 July 2013 - 23 August 2013

Reliability:

other: not applicable.

Rationale for reliability incl. deficiencies:

other: Not a Reach requirement

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2014

Materials and methods

Test guideline

Qualifier:

no guideline available

Principles of method if other than guideline:

The critical micelle concentration (CMC) of the test substance was determined since the test substance is surface active. For surface active substances which form micelles in solution, the surface tension decreases with increasing concentration until the CMC is reached. At concentrations above the CMC, the surface tension remains constant. The CMC was determined by measuring the surface tension of test substance solutions at different test substance concentrations. The concentrations were expressed as mg test substance/L (i.e. not corrected for purity). The surface tension measurements were performed using the OECD Harmonized ring method.

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Sodium 2-sulphonatoethyl laurate

EC Number:

230-949-8

EC Name:

Sodium 2-sulphonatoethyl laurate

Cas Number:

7381-01-3

Molecular formula:

C14H28O5S.Na

IUPAC Name:

sodium 2-sulphonatoethyl laurate

Test material form:

other: powder and needles

Details on test material:

- Name of test material (as cited in study report): Sodium Lauroyl Isethionate
- Description: White powder and needles
- Storage condition of test material: At room temperature in the dark, in well-sealed container
- Expiration date of the batch: 01 December 2014
- Hygroscopic: Yes

Results and discussion

Results:

The plot of the surface tension of the test solutions as function of log C is shown below. The CMC was determined from the intersection of the two trendlines y1 and y2. Trendline y1 was obtained from the concentrations 1.00- 1009 mg/L. Trendline y2 was obtained from the concentrations 5006 - 25001 mg/L. The intersection was calculated to be log C = 3.42. It corresponded with a CMC of 2.6 g/L. It has to be noted that the CMC was above the water solubility (1.29 g/L: see endpoint 4.8 ) indicating that the CMC is likely influenced by minor components present in the test substance.

Any other information on results incl. tables

Surface tension measurements test solution 1.0 mg/L

Measurement	Time passed [minutes]	Surface tension [mN/m]
		individual	mean	mean corrected (1)
1	15	74.0
2	16	74.1	74.0	75.5
3	16	73.9
4	17	74.1
5	18	74.0

(1) Multiplied by Φb followed by correction according to Harkins-Jordan.

 

 

Surface tension measurements test solution 10.1mg/L

Measurement	Time passed [minutes]	Surface tension [mN/m]
		individual	mean1	mean corrected (2)
1	16	61.9
2	16	62.0	68.6	69.9
3	17	63.0
4	18	64.1
5	19	64.4
6	19	68.5
7	20	68.6
8	21	68.8
9	22	68.4
10	23	68.6

(1) Mean calculated from measurements 6 to 10.

(2) Multiplied by Φb followed by correction according to Harkins-Jordan.

 

Surface tension measurements test solution 100.7 mg/L

Measurement	Time passed [minutes]	Surface tension [mN/m]
		individual	mean	mean corrected (1)
1	15	56.1
2	15	55.9	55.9	56.0
3	16	56.0
4	17	55.8
5	17	55.9

(1) Multiplied by Φb followed by correction according to Harkins-Jordan.

 

Surface tension measurements test solution 10009.2 mg/L

Measurement	Time passed [minutes]	Surface tension [mN/m]
		individual	Mean (1)	Mean corrected (2)
1	15	39.4
2	16	38.2	37.9	36.8
3	17	37.1
4	18	37.8
5	19	38.1
6	19	37.8
7	20	37.9
8	21	37.8

(1) Mean calculated from measurements 4 to 8.

(2) Multiplied byΦb followed by correction according to Harkins-Jordan.

 

Surface tension measurements test solution 5005.7 mg/L

Measurement	Time passed [minutes]	Surface tension [mN/m]
		individual	Mean	mean corrected (1)
1	17	33.9
2	18	33.8	33.9	32.0
3	18	34.1
4	19	33.8
5	20	33.7

(1) Multiplied by Φb followed by correction according to Harkins-Jordan.

 

 

Surface tension measurements test solution 10007.5 mg/L

Measurement	Time passed [minutes]	Surface tension [mN/m]
		individual	mean	mean corrected (1)
1	15	32.4
2	15	32.5	32.3	30.4
3	16	32.2
4	17	32.2
5	18	32.3

(1) Multiplied by Φb followed by correction according to Harkins-Jordan.

 

Surface tension measurements test solution 25001.0 mg/L

Measurement	Time passed [minutes]	Surface tension [mN/m]
		individual	Mean (1)	Mean corrected (2)
1	16	33.8
2	17	34.0	32.1	30.2
3	18	31.9
4	19	32.2
5	19	31.8
6	20	32.1
7	21	32.3

(1) Mean calculated from measurements 3 to 7.

(2) Multiplied by Φb followed by correction according to Harkins-Jordan.

 

Applicant's summary and conclusion

Conclusions:

The critical micelle concentration CMC of the test substance was determined to be 2.6 g/L by measuring the surface tension of test substance solutions at different test substance concentrations.