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Water solubility
Administrative data
Link to relevant study record(s)
- Endpoint:
- water solubility
- Remarks:
- critical micelle concentration
- Type of information:
- experimental study
- Adequacy of study:
- supporting study
- Study period:
- 30 March 2020 to 29 April 2020
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Qualifier:
- according to guideline
- Guideline:
- other: ISO Guide 4311
- Version / remarks:
- 1979
- Deviations:
- no
- Qualifier:
- according to guideline
- Guideline:
- other: EC Method A.5
- Version / remarks:
- 2008
- Deviations:
- no
- Qualifier:
- according to guideline
- Guideline:
- other: OECD Guideline 115 (Surface Tension)
- Version / remarks:
- 1995
- Deviations:
- no
- GLP compliance:
- yes (incl. QA statement)
- Remarks:
- Date of Inspection: 10-17 December 2019; Date of Signature on Certificate: 24 February 2020
- Type of method:
- other: critical micelle concentration (CMC)
- Remarks:
- CMC was being investigated as a surrogate water solubility value as the test item is surface active
- Key result
- Remarks on result:
- not determinable
- Conclusions:
- It is not technically possible to determine the Critical Micelle Concentration (CMC) of the test item.
- Executive summary:
As the surface tension study indicated that the substance is a surface active, traditional water solubility tests were not considered applicable and critical micelle concentration is considered an effective surrogate value for water solubility.
Critical micelle concentration was attempted to be determined by investigating the surface tension of a range of aqueous sample solutions of differing concentrations, using a procedure based on Method A.5 Surface Tension of Commission Regulation (EC) No 440/2008 of 30 May 2008, Method 115 of the OECD Guidelines for Testing of Chemicals, 27 July and ISO Guide 4311, 1979.
However, the surface tension decreased with increasing concentration and no constant value was reached at 10 g/L and it was not possible to estimate the critical micelle concentration from the data.
As the test item is known to be instable in water, with the amount of constituent 1 rapidly degrading to constituent 2, it is not considered possible to determine the critical micelle concentration of the test item.
- Endpoint:
- water solubility
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 01 July 2020 to 02 October 2020
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Reason / purpose for cross-reference:
- reference to same study
- Qualifier:
- according to guideline
- Guideline:
- EPA OPPTS 830.7840 (Water Solubility)
- Version / remarks:
- 1998
- Deviations:
- no
- Qualifier:
- according to guideline
- Guideline:
- EU Method A.6 (Water Solubility)
- Version / remarks:
- 2016
- Deviations:
- no
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 105 (Water Solubility)
- Version / remarks:
- 1995
- Deviations:
- no
- GLP compliance:
- yes
- Remarks:
- Date of inspection: 10-17 December 2019 Date on certificate: 24 February 2020
- Type of method:
- flask method
- Key result
- Water solubility:
- 36.7 g/L
- Conc. based on:
- other: Reaction product of N-phenyl-diethanolamine with a single molecule of formaldehyde constituent
- Temp.:
- 20 °C
- pH:
- 6.6
- Key result
- Water solubility:
- 32.1 g/L
- Conc. based on:
- other: N-phenyl-diethanolamine constituent
- Temp.:
- 20 °C
- pH:
- 6.6
- Details on results:
- Preliminary Result: The content of test item dissolved in the water sample was 37.5 g/L
- Conclusions:
- The water solubility of the reaction product of N-Phenyl-diethanolamine with a single molecule of formaldehyde at 20°C was determined to be 36.7 g/L. The water solubility of N-Phenyl-diethanolamine at 20°C was determined to be 32.1 g/L, both at a pH of 6.6.
- Executive summary:
The water solubility of the test item was assessed using the flask method in accordance with OECD 105 (1995) and EC Guideline A.6 (1995). The two major components of the test item are N-Phenyl-diethanolamine and the reaction product of N-Phenyl-diethanolamine with a single molecule of formaldehyde. Therefore two independent validated analytical methods were used to determine the water solubility. The mean water solubility of the reaction product of N-Phenyl-diethanolamine with a single molecule of formaldehyde at 20°C was 36.7 g/L and the mean water solubility of N-Phenyl-diethanolamine at 20°C was 32.1 g/L at a mean pH of 6.6.
Referenceopen allclose all
Preliminary Test
The results of the test solutions prepared on the first day to estimate the CMC are given in Table 1 to Table 5. The individual measurements were obtained with a coefficient of variation of < 0.2 mN/m.
Table 1
Surface Tension of the 1.0000 mg/L Test Item Solution
Measurement |
Time passed after measurement start |
Surface tension |
|
individual σ multiplied by Harkins-Jordan corrected value |
mean σ
|
||
1 |
43.63 |
71.79 |
71.68 |
2 |
70.22 |
71.71 |
|
3 |
97.98 |
71.66 |
|
4 |
125.66 |
71.62 |
|
5 |
152.88 |
71.60 |
|
Table 2
Surface Tension of the 10.043 mg/L Test Item Solution
Measurement |
Time passed after measurement start |
Surface tension |
|
individual σ multiplied by Harkins-Jordan corrected value |
mean σ
|
||
1 |
42.98 |
72.08 |
72.03 |
2 |
70.00 |
72.04 |
|
3 |
97.71 |
72.00 |
|
4 |
124.66 |
72.01 |
|
5 |
152.97 |
71.99 |
|
Table 3
Surface Tension of the 99.733 mg/L Test Item Solution
Measurement |
Time passed after measurement start |
Surface tension |
|
individual σ multiplied by Harkins-Jordan corrected value |
mean σ
|
||
1 |
42.71 |
71.43 |
71.36 |
2 |
70.71 |
71.36 |
|
3 |
96.97 |
71.36 |
|
4 |
124.85 |
71.35 |
|
5 |
152.65 |
71.33 |
|
Table 4
Surface Tension of the 1025.8 mg/L Test Item Solution
Measurement |
Time passed after measurement start |
Surface tension |
|
individual σ multiplied by Harkins-Jordan corrected value |
mean σ
|
||
1 |
42.51 |
66.28 |
66.20 |
2 |
68.96 |
66.23 |
|
3 |
95.23 |
66.20 |
|
4 |
121.25 |
66.18 |
|
5 |
147.91 |
66.14 |
|
Table 5
Surface Tension of the 10017 mg/L Test Item Solution
Measurement |
Time passed after measurement start |
Surface tension |
|
individual σ multiplied by Harkins-Jordan corrected value |
mean σ
|
||
1 |
39.93 |
50.35 |
50.11 |
2 |
65.29 |
50.17 |
|
3 |
90.66 |
50.08 |
|
4 |
115.73 |
50.00 |
|
5 |
141.28 |
49.93 |
|
The surface tension measured decreased with increasing concentration. As no constant value was reached at 10 g/L, it is not possible to estimate the critical micelle concentration from the data.
Results - the reaction product of N-phenyl-diethanolamine with a single molecule of formaldehyde
The results for the samples taken at 24, 48 and 72 hours are given in Table 1 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 analysed concentrations.
No test item was detected in the pre-treated sample from the blank water mixture.
Table 1
Stirring time |
Peak area (µVxsec) |
Analysed concentration |
Mean |
Maximum difference |
pH |
24 |
48673 |
36.8 |
36.7 |
2.12 |
6.8 |
48 |
49074 |
37.1 |
|
|
6.6 |
72 |
48502 |
36.3 |
|
|
6.5 |
Results - N-phenyl-diethanolamine
The results for the samples taken at 24, 48 and 72 hours are given in Table 2.
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 analytical standard is given as the mean value of the analysed concentrations.
No analytical standard was detected in the pre-treated sample from the blank water mixture.
Table 2
Stirring time |
Peak area (µVxsec) |
Analyzed concentration |
Mean |
Maximum difference |
pH |
24 |
48673 |
32.6 |
32.1 |
7.9 |
6.8 |
48 |
49074 |
33.1 |
|
|
6.6 |
72 |
48052 |
30.6 |
|
|
6.5 |
Description of key information
Critical micelle concentration could not be determined; OECD 115 ; Jovic Madzarevic, Z. (2020)
36.7 g/L for reaction product of n-phenyl-diethanolamine with formaldehyde constituent, 32.1 g/L for n-phenyl-diethanolamine constituent; OECD 105; Petrovic, D. (2020)
Key value for chemical safety assessment
- Water solubility:
- 32.1 g/L
- at the temperature of:
- 20 °C
Additional information
Results from the surface tension study indicated the substance could be considered surface active. A CMC study was performed first however it was not possible to determine the CMC which indicated that the substance does not behave as a true surfactant.
A traditional water solubility study was therefore performed and the water solubility of the two main constituents determined. The value of 32.1 g/L for the n-phenyl-diethanolamine constituent was used as the key value for this endpoint. It is the most appropriate value to use for the chemical safety assessment, due to rapid abiotic transformation in aqueous environments where the reaction product of N-phenyl-diethanolamine with a single molecule of formaldehyde constituent is transformed to the n-phenyl-diethanolamine constituent, with a half-life of 9 minutes at 25 °C (OECD 111).
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