Sodium 2-stearoyllactate

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

27 - 31 Jan 2020

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Reason / purpose for cross-reference:

reference to same study

Principles of method if other than guideline:

- Principle of test: due to the complexity of the substance and since surface activity was expected (based on structure), the water solubility has been determined in terms of the critical micelle concentration (CMC).
- Short description of test conditions: see "Any other information on materials and methods incl. tables"
- Parameters analysed / observed: surface activity as function of the concentration in water of the test item

GLP compliance:

no

Type of method:

other: critical micelle concentration

Water solubility:

5.34 mg/L

Temp.:

20 °C

Remarks on result:

other: pH not reported

Results

The determination of the critical micelle concentration (CMC) was conducted by measuring the surface tension of the test item at 20 ± 0.5 °C and at different concentrations (see table below). For the evaluation of the CMC, a graph ‘Test Concentration’ vs. ‘Surface Tension’ was created.

 

Concentration [mg/L]	Surface Tension (1) [mN/m]	Time (2) [h]	Time (3) [min]	Temp. (4) [°C]
1.00	53.23	92.2	94	19.8 - 19.9
2.01	49.98	88.6	96	19.8 – 20.2
2.51	48.26	70.2	74	19.8 – 20.1
3.01	46.04	68.2	81	20.1 – 20.2
3.52	46.94	65.5	87	19.8 – 20.1
4.02	45.01	46.3	67	19.7 – 19.9
4.52	43.06	43.6	84	19.7 – 19.9
5.02	42.49	40.7	70	19.9 – 20.0
6.03	40.33	23.3	104	20.0 – 20.1
8.04	39.89	21.3	71	19.9 – 20.1
10.0	37.09	18.1	139	19.8 – 20.1

(1) The density of each test solution was in the range of 0.998 to 1.011 g/mL

(2) Time from preparation of the test solution (stored in an air-conditioned room at 20 °C) until start of the measurement

(3) Time from start of the measurement till end of the surface tension measurement

(4) Temperature of the test solution during the determination of the respective surface tension

 

 

Calculations

Equation R-squared of the “fall phase”: y1 = -2.6218x + 55.27; R² = 0.9617

Equation R-squared of the “plateau phase”: y2 = -0.81x + 45.58; R² = 0.85

The critical micelle concentration is calculated from the point of intersection of the two lines y1

and y2:

-2.6218x + 55.27 = -0.81x + 45.58

x = 5.34

 

 

Performance Verification of the Analytical System

For the performance verification of the analytical system a reference study was conducted, were the surface tension of the n-heptane was determined on the 2019-06-13 to be 20.22 ± 0.05 mN/m (20 °C) for the platinum iridium ring RI 21 (internal no. 1) and is within the acceptable range of 20.23 ± 0.22 mN/m.

 

Validity Criteria

The temperatures of the test solutions were 20 ± 0.5 °C.

 

Conclusion

The determination of the critical micelle concentration of the test item resulted in a value of: 5.34 mg/L (20 °C)

Conclusions:

The test item has a water solubility of 5.34 mg/L

Description of key information

Water solubility: 5.34 mg/L at 20 °C (expressed in terms of the critical micelle concentration, OECD Guideline 115)

Key value for chemical safety assessment

Water solubility:

5.34 mg/L

at the temperature of:

20 °C