N-Phenyl-diethanolamine, reaction products with formaldehyde

Water solubility

Link to relevant study record(s)

Reference

Reference 1

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

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 [seconds]	Surface tension (mN/m)
		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 [seconds]	Surface tension (mN/m)
		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 [seconds]	Surface tension (mN/m)
		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 [seconds]	Surface tension (mN/m)
		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 [seconds]	Surface tension (mN/m)
		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. 

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. 

Reference 2

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

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 [hours]	Peak area (µVxsec)	Analysed concentration [g/L]	Mean [g/L]	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 [hours]	Peak area (µVxsec)	Analyzed concentration [g/L]	Mean [g/L]	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

 

 

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.

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).