Quaternary ammonium compounds, coco alkyltrimethyl, chlorides

Water solubility

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 21 August, 2008 to 04 November, 2008

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

other: Modified flask method (graduated cylinder method)

Key result

Water solubility:

328 g/L

Temp.:

10 °C

pH:

7.08

Details on results:

pH Concentration: 328 g/L
Stable: yes
Temperature effects: No

Water solubility of the test substance:

Double Distilled Water: 328 g/L (at 10, 20, 30°C)

Hydrochloric acid (pH 4): 328 g/L (at 10, 20, 30°C)

Sodium hydroxide (pH 9): 328 g/L (at 10, 20, 30°C)

pH values of the test substance solution in double distilled water at test temperatures:

Temperature (°C)	Replicate	pH before adjustment	pH after adjustment
30	1	8.49	7.07
	2	8.44	7.07
20	1	8.42	7.04
	2	8.40	7.03
10	1	8.29	7.08
	2	8.38	7.08

pH values of the test substance dissolved in hydrochloric acid solution (pH 4) at test temperatures:

Temperature (°C)	Replicate	pH before adjustment	pH after adjustment
30	1	8.38	4.08
	2	8.38	3.95
20	1	8.39	3.97
	2	8.42	4.09
10	1	8.30	4.08
	2	8.31	4.00

pH values of the test substance dissolved in sodium hydroxide solution (pH 9)at test temperatures:

Temperature (°C)	Replicate	pH before adjustment	pH after adjustment
30	1	8.43	9.06
	2	8.42	8.99
20	1	8.49	9.10
	2	8.44	9.02
10	1	8.32	9.02
	2	8.44	9.01

Conclusions:

Under the conditions of the study, the aqueous solubility of the test substance was determined to be 328 g/L (very soluble).

Executive summary:

A study was conducted to determine the water solubility of the test substance, TMAC C using a modified flask method (graduated cylinder method), according to the OECD 105 Guideline, in compliance with GLP. The solubility of the test substance in double distilled water, hydrochloric acid solution at pH 4 and sodium hydroxide solution at pH 9 was determined at 10, 20 and 30 ± 0.5°C with pre-incubation at 35 ± 0.5 °C. The solubility of the test substance was found to be independent of temperature and pH. Under the conditions of the study, the aqueous solubility of the test substance was determined to be 328 g/L (very soluble) (Bodsch, 2008).

 

However, a more suitable critical micelle concentration (CMC) based water solubility of 1 g/L, for surfactants, determined in the surface tension study has been taken forward for the hazard and exposure assessment.

Reference 2

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From April 24, 2008 to April 25, 2008

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

other: OECD Guideline 115 (Surface Tension of Aqueous Solutions)

Version / remarks:

27 July 1995

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: EU Method A.5 (Surface Tension)

Version / remarks:

30 May 2008

Deviations:

no

Principles of method if other than guideline:

Below the CMC, a surfactant is considered to be thermodynamically soluble in the water; whereas above the CMC, the solubility of a surfactant in water has been exceeded and the excess surfactant aggregates to form micelles. These micelles have significantly less effect on the surface tension of a solution and are considered not to be in solution. Thus, the water solubility of a surfactant may be expressed in terms of the CMC.

GLP compliance:

yes (incl. QA statement)

Type of method:

other: by determining the surface tension of a range of aqueous sample solutions of differing concentration

Key result

Water solubility:

ca. 1 000 mg/L

Conc. based on:

test mat.

Temp.:

20 °C

Remarks on result:

other: CMC determined

Details on results:

Please see below table.

Results

Table1: Surface tension of 1 g/L aqueous solution of test substance

Measurement #	Measurement time (min)*	Surface tension [mN/m]	Temperature [deg C]
1	21.9	24.14	20
2	22.1	24.11	20
3	22.4	24.08	20
4	22.6	24.01	20
5	22.8	24.03	20
6	23	24.02	20
7	23.2	24.01	20
8	23.5	24.01	20
9	23.7	23.98	20
10	23.9	24.03	20
MV	-	24.04	20
SD	-	0.05	0

Table 2: Surface tension of test substance at different concentrations

Concentration [g/L]	Surface tension [mN/m]	Mean temperature [deg C]
0.05	45.52	19.9
0.2	31.81	20
0.35	30.29	19.9
0.5	24.6	20
0.75	24.13	20
1	24.04	20
5	31.88	19.7
10	33.98	19.9

The plot of log₁₀[concentration (g/L)] versus surface tension (mN/m) can be found under illustration section of the IUCLID' :

The minimum at 1 g/L and 24.04 mN/m represents the critical micelle concentration. The CMC of an aqueous solution of the test substance was determined to be 1 g/L.

Discussion

The critical micelle concentration (CMC) is an important characteristic of a surfactant. At low concentrations of surfactant, the surface tension of water is only slightly affected. Increasing the concentration but before reaching the CMC, the surface tension changes significantly; After reaching the CMC and above, the surface tension remains relatively constant or changes with a much more gradual slope. Below the CMC, a surfactant is considered to be thermodynamically soluble in the water; whereas above the CMC, the solubility of a surfactant in water has been exceeded and the excess surfactant aggregates to form micelles. These micelles have significantly less effect on the surface tension of a solution and are considered not to be in solution. Thus, the water solubility of a surfactant may be expressed in terms of the CMC.

Conclusions:

Under the study conditions, the the CMC as water solubility of the test substance was determined to be 1000 mg/L at 20.0 ± 0.5°C.

Executive summary:

A study was conducted to determined the water solubility of the test substance, TMAC C (99.6% active) based on critical micelle concentration (CMC), according to OECD Guideline 115 and EU Method A.5, in compliance with GLP. Due to the surface activity of the test substance, the CMC value was considered as a water soluibility equivalent in accordance with the ECHA R.7a Guidance. Under the study conditions, the CMC of the test substance was determined to be 1000 mg/L at 20.0 ± 0.5°C (Bodsch, 2008).

Description of key information

Water solubility according to OECD 105 Guideline was determined to be 328 g/L (independent of pH and temperature). However, a more suitable critical micelle concentration (CMC) based water solubility determined in the surface tension study has been taken forward for the hazard and exposure assessment.

Key value for chemical safety assessment

Water solubility:

1 000 mg/L

at the temperature of:

20 °C

Additional information

The water solubility was determined based on critical micelle concentration (CMC) from the surface tension study (Bosch, 2008) as well as according to OECD Guideline 105 (Bodsch, 2008).