1-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-(C16-18(even numbered) and C18 unsaturated acyl) derivs., hydroxides, inner salts

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:

June 27, 2017 - November 02, 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

no guideline available

Principles of method if other than guideline:

The Critical Micelle Concentration (CMC) was determined by measuring the surface tension of test item solutions at different test item concentrations. 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.

GLP compliance:

yes (incl. QA statement)

Type of method:

other: OECD harmonized ring method

Specific details on test material used for the study:

- Analytical purity: 100% (UVCB)
- Purity test date: 06 June 2017
- Lot/batch No.: 180517GT41
- Expiration date of the lot/batch: 31 December 2017
- Appearance: Beige pasty solid
- Storage: At room temperature

Key result

Water solubility:

39.9 mg/L

Conc. based on:

test mat.

Temp.:

20 °C

Remarks on result:

other: Expressed as Critical Micelle Concentration (CMC)

The CMC was determined from the intersection of the two trend lines y1 and y2. Trendline y1 was obtained using the data of the test solutions with test item concentrations of 1.0129, 5.0341, 10.020 and 30.102 mg/L. Trendline y2 was obtained from the mean surface tension of the test solutions with test item concentrations of 200.49, 499.5 and 999.01 mg/L. The intersection was calculated to be at a log C value of 1.60. It corresponded with a CMC of 39.9 mg/L.

Conclusions:

The Critical Micelle Concentration (CMC) of the test item was determined by measuring the surface tension of test item solutions at different test item concentrations. The CMC was 39.9 mg/L.

Executive summary:

The Critical Micelle Concentration (CMC) of the test item was determined by measuring the surface tension of test item solutions at different test item concentrations, according to the OECD harmonized ring method. The CMC was 39.9 mg/L.

Reference 2

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

June 27, 2017 - December 11, 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

GLP compliance:

yes (incl. QA statement)

Type of method:

flask method

Specific details on test material used for the study:

- Analytical purity: 100% (UVCB)
- Purity test date: 06 June 2017
- Lot/batch No.: 180517GT41
- Expiration date of the lot/batch: 31 December 2017
- Appearance: Beige pasty solid
- Storage: At room temperature

Water solubility:

100 g/L

Conc. based on:

test mat.

Temp.:

20 °C

RESULTS

Preliminary test

Preliminary test – 10 g/L. The 10 g/L solution had dissolved completely (visual observation) which was confirmed by the result of the analysis: based on the response for C18:1 amido propyl betaine, the content of test item dissolved in the water sample was 10.8 g/L.

Preliminary test – 100 g/L. The 100 g/L solution had become a green/yellow gel that could just be stirred. Centrifugation did not give phase separation. Therefore the gel was analysed. Concentration measured was the nominal concentration: based on the response for C18:1 amido propyl betaine, the content of test item dissolved in the water sample was 98.8 g/L.

Main study

Main study – 10 g/L. The results for the samples taken at 24, 48 and 72 hours are given in the table below. The maximum difference of the concentrations determined in the 24, 48 and 72 hour test

samples was ≤ 15%. Based on this, the water solubility of the test item is given as the mean value of the analyzed concentrations. No test item was detected in the pretreated sample from the corresponding blank water mixture.

Stirring time [hours]	Prepared concentrations [g/L]	Analyzed concentrations  [g/L]	Recovery [%]	pH
24 48 72	10.1 10.1 10.1	12.2 11.0 11.8	121 109 117	5.8 6.0 6.0

Main study – 100 g/L. The results for the samples stirred for 24, 48 and 72 hours are given in the table below. The maximum difference of the concentrations determined in the test samples stirred for 24, 48 and 72 hour was 18% and 7.0% in the test samples stirred for 48 and 72 hours. Based on this, the water solubility of the test item is given as the mean value of the analyzed concentrations after 48 and 72 hours of stirring. A very small response at the retention time of the test item was detected in the pretreated sample from the corresponding blank water mixture. The contribution to the test samples was negligible.

Stirring time [hours]	Prepared concentrations [g/L]	Analyzed concentrations  [g/L]	Recovery [%]	pH
24 48 72	100 101 102	84.0 93.4 100	84 93 99	n.a.  n.a.  n.a.

Testing at concentrations > 100 g/L was not possible since the mixture could not be stirred anymore.

Conclusions:

Based on the response for C18:1 amido propyl betaine at m/z 425.3 > m/z 322.3, it was concluded that the test item has completely dissolved at a nominal test item concentration of 10 g/L and that at 100 g/L maximum solubility has been reached since recovery was lower.

Executive summary:

The water solubility of the test item was determined in a GLP-compliant study performed in accordance with EU Method A.6 and OECD Guideline No. 105. Based on the response for C18:1 amido propyl betaine, it was concluded that the test item has completely dissolved at a nominal test item concentration of 10 g/L and that at 100 g/L maximum solubility has been reached since recovery was lower.

Description of key information

The Critical Micelle Concentration (CMC) of the test item was determined by measuring the surface tension of test item solutions at different test item concentrations, according to the OECD harmonized ring method. The CMC was 39.9 mg/L. The water solubility of the test item was otherwise determined in a GLP-compliant study performed in accordance with EU Method A.6 and OECD Guideline No. 105. Based on the response for C18:1 amido propyl betaine, it was concluded that the test item has completely dissolved at a nominal test item concentration of 10 g/L and that at 100 g/L maximum solubility has been reached since recovery was lower.

As the test item proved to be surface active, the Critical Micelle Concentration is preferred to characterize the water solubility of the test item.

Key value for chemical safety assessment

Water solubility:

39.9 mg/L

at the temperature of:

20 °C

Additional information

The water solubility of the test item was determined in two GLP-compliant studies performed in accordance with standard methods, without deviations. In a first study, the Critical Micelle Concentration was determined by measuring the surface tension of test item solutions at different concentrations. In a second study, the water solubility was determined by measuring the saturation limit of test item solutions at different concentrations. Both studies are considered as reliable (Klimisch 1) but as the test item proved to be surface active, the Critical Micelle Concentration is preferred to characterize the water solubility of the test item. The first study is thus selected as a key study for the endpoint whereas the second study is selected as a supporting study.