N-(2-hydroxyethyl)dodecanamide

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

17 August 2017 - TBC

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Study was conducted in accordance with international guidelines and in accordance with GLP. All guideline validity criteria were met.

Qualifier:

according to guideline

Guideline:

EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)

Version / remarks:

Regulation (EC) 440/2008 of 30 May 2008

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

Version / remarks:

13 April 2004

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Details on sampling:

- Sampling intervals for the parent/transformation products:
- Sampling method: The sample solutions were taken from the water bath at 24 and 120 hours. The pH of each solution recorded. The concentration of test item in the sample solutions was determined by liquid chromatography – mass spectroscopy (LC-MS).
- Sampling methods for the volatile compounds, if any: Not applicable.
- Sampling intervals/times for pH measurements: 24 and 120 hours.
- Sampling intervals/times for sterility check: Not reported, assumed not to be conducted.
- Sample storage conditions before analysis: Not reported, assumed analysis was conducted without sample stprage.
- Other observation, if any (e.g.: precipitation, color change etc.):

Buffers:

- pH: 4
- Type and final molarity of buffer:
- Composition of buffer: Citric acid 0.06 mol/dm3, Sodium chloride 0.04 mol/dm3, Sodium hydroxide 0.07 mol/dm3.


- pH: 7
- Type and final molarity of buffer:
- Composition of buffer: Disodium hydrogen orthophosphate (anhydrous) 0.03 mol/dm3, Potassium dihydrogen orthophosphate 0.02 mol/dm3, Sodium chloride 0.02 mol/dm3.


- pH: 9
- Type and final molarity of buffer:
- Composition of buffer: Disodium tetraborate 0.01 mol/dm3, Sodium chloride 0.02 mol/dm3.


The buffer solutions were passed through a 0.2 µm membrane filter to sterilise and subjected to ultrasonication and degassing with nitrogen to minimize dissolved oxygen.

Details on test conditions:

TEST SYSTEM
- Type, material and volume of test flasks, other equipment used:
- Sterilisation method:
- Lighting:
- Measures taken to avoid photolytic effects:
- Measures to exclude oxygen:
- Details on test procedure for unstable compounds:
- Details of traps for volatile, if any
- If no traps were used, is the test system closed/open
- Is there any indication of the test material adsorbing to the walls of the test apparatus?
TEST MEDIUM
- Volume used/treatment
- Kind and purity of water:
- Preparation of test medium:
- Renewal of test solution:
- Identity and concentration of co-solvent:
OTHER TEST CONDITIONS
- Adjustment of pH:
- Dissolved oxygen:

Duration:

120 h

pH:

4

Temp.:

50 °C

Initial conc. measured:

4.89 mg/L

Remarks:

Mean value of two replicants.

Duration:

120 h

pH:

7

Temp.:

50 °C

Initial conc. measured:

4.84 mg/L

Remarks:

Mean value of two replicants.

Duration:

120 h

pH:

9

Temp.:

50 °C

Initial conc. measured:

4.94 mg/L

Remarks:

Mean value of two replicants.

Number of replicates:

Standard solution: Four replicates.
Test solution: Two per pH level

Positive controls:

not specified

Remarks:

Not applicable, preliminary test.

Negative controls:

not specified

Remarks:

Not applicable, preliminary test.

Preliminary study:

Less than 10% hydrolysis after 5 days at 50 °C at pH 4, 7 & 9, equivalent to half-life > 1 year at 25 °C.

Transformation products:

no

Remarks on result:

hydrolytically stable based on preliminary test

Remarks on result:

hydrolytically stable based on preliminary test

Data Evaluation:

The response factors of the standard peak areas (unit total peak area per mg/L) were calculated using Equation 1:

 

Equation 1:

RF = R_STD/C_STD

 

Where:

RF = response factor for the standard solution

R_STD= total peak area for the standard solution

C_STD= concentration for the standard solution (mg/L)

 

The concentration of the sample solution (g/L) was calculated using Equation 2:

 

Equation 2:

C = (R_SPL/RF_STD) x (D/1,000)

 

Where:

RF = sample solution concentration (g/L)

R_SPL= mean total peak area for the sample solution

RF_STD= mean response factor for the standard solutions (unit total peak area per mg/L)

D = dilution factor (2) 

 

 

Calculation of the Degree of Hydrolysis

The decrease in concentration or the degree of hydrolysis was calculated using Equation 3:

 

Equation 3:

Degree of hydrolysis in % = [(C₀– C_t)/C₀] x 100

 

Where:

C₀= concentration of time 0

C_t= concentration of time t

 

 

Results – Preliminary Test/Tier 1:

The mean peak areas relating to the standard and sample solutions for the initial time, 24 hour and 120-hour time points for pH 4, 7 and 9 are shown in Tables 3 – 5:

 

Table 3:          Peak Areas – Initial

Solution	Mean peak area
Standard 2.54 mg/L	2.492 x 10^6
Standard 2.52 mg/L	2.466 x 10^6
Sample A pH 4, initial	2.428 x 10^6
Sample B pH 4, initial	2.476 x 10^6
Sample A pH 7, initial	2.428 x 10^6
Sample B pH 7, initial	2.418 x 10^6
Sample A pH 9, initial	2.476 x 10^6
Sample B pH 9, initial	2.483 x 10^6
Standard 2.54 mg/L	2.602 x 10^6
Standard 2.52 mg/L	2.574 x 10^6

 

 

Table 4:          Peak Areas – 24 Hour

Solution	Mean peak area
Standard 2.54 mg/L	2.694 x 10^6
Standard 2.52 mg/L	2.664 x 10^6
Sample A pH 4, 24-Hr	2.565 x 10^6
Sample B pH 4, 24-Hr	2.584 x 10^6
Sample A pH 7, 24-Hr	2.578 x 10^6
Sample B pH 7, 24-Hr	2.564 x 10^6
Sample A pH 9, 24-Hr	2.637 x 10^6
Sample B pH 9, 24-Hr	2.574 x 10^6
Standard 2.54 mg/L	2.770 x 10^6
Standard 2.52 mg/L	2.743 x 10^6

 

 

Table 5:          Peak Areas – 120 Hour

Solution	Mean peak area
Standard 2.54 mg/L	1.405 x 10^6
Standard 2.54 mg/L	1.338 x 10^6
Sample A pH 4, 120-Hr	1.267 x 10^6
Sample B pH 4, 120-Hr	1.266 x 10^6
Sample A pH 7, 120-Hr	1.184 x 10^6
Sample B pH 7, 120-Hr	1.181 x 10^6
Sample A pH 9, 120-Hr	1.184 x 10^6
Sample B pH 9, 120-Hr	1.185 x 10^6
Standard 2.54 mg/L	1.260 x 10^6
Standard 2.54 mg/L	1.238 x 10^6

 

 

The test item concentrations at the given time points are shown in Tables 6 – 8:

 

Table 6:          pH 4 at 50.0 ± 0.5°C

Time (hours)	Concentration (mg/L)		Percentage of mean initial concentration
	A	B	A	B
0	4.84	4.94	-	-
24	4.77	4.81	97.5	98.2
120	4.91	4.91	100	100

Less than 10% hydrolysis after 5 days at 50 °C, equivalent to half-life > 1 year at 25 °C.

 

Table 7:          pH 7 at 50.0 ± 0.5°C

Time (hours)	Concentration (mg/L)		Percentage of mean initial concentration
	A	B	A	B
0	4.84	4.83	-	-
24	4.79	4.77	99.2	98.7
120	4.59	4.58	95.0	94.7

Less than 10% hydrolysis after 5 days at 50 °C, equivalent to half-life > 1 year at 25 °C.

 

 

Table 8:          pH 9 at 50.0 ± 0.5°C

Time (hours)	Concentration (mg/L)		Percentage of mean initial concentration
	A	B	A	B
0	4.92	4.95	-	-
24	4.90	4.79	99.3	97.0
120	4.59	4.50	93.0	93.1

Less than 10% hydrolysis after 5 days at 50 °C, equivalent to half-life > 1 year at 25 °C.

 

 

Validation:

The linearity of the detector response with respect to concentration was assessed over the nominal concentration range of 0.1 to 4 mg/L. The plot was found to be 1st order with a correlation coefficient (r) of 1.000.

 

 

Discussion:

The concentration of each solution did not exceed the lesser of 0.01 mol/L or half the water solubility.

 

No significant peaks were observed at the approximate retention time of the test item on analysis of any matrix blank solutions.

 

The pH of all the test solutions remained stable throughout testing (< ±0.1 pH unit) of the target pH 4, 7 and 9.

Conclusions:

The estimated half-lives at 25 °C of the test item is > 1 year at pH 4, pH 7 and pH 9.

Executive summary:

EU Method C.7. – The hydrolysis of the test item as a function of pH was determined using a procedure designed to be compatible with Method C.7., Degradation — Abiotic Degradation: Hydrolysis as a Function of pH, of Commission Regulation (EC) No 440/2008 of 30 May 2008.

Sterile buffer solutions at pH’s 4.0, 7.0 and 9.0 were prepared, passed through a 0.2 µm membrane filter to sterilise and subjected to ultrasonication and degassing with nitrogen to minimise dissolved oxygen.  Stock solutions of test item were prepared at a nominal concentration of 5 mg/L in the three buffer solutions; a 1% co-solvent of acetonitrile was used to aid solubility.  The stock solutions were split into individual glass vessels, sealed with minimal headspace, for each data point.  These sample solutions were shielded from light whilst maintained at the test temperature.  Sample solutions at pH 4, 7 and 9 were maintained at 50.0 ± 0.5 °C for a period of 120 hours.

The test item achieved less than 10% hydrolysis after 5 days at 50 °C at pH 4, 7 & 9, equivalent to half-life > 1 year at 25 °C.  The concentration of each solution did not exceed the lesser of 0.01 mol/L or half the water solubility.  The pH of all the test solutions remained stable throughout testing (< ±0.1 pH unit) of the target pH 4, 7 and 9.

Description of key information

Hydrolysis: Half-life > 1 year at 25.0°C; EU Method C.7.; R. Butler (2018)

Key value for chemical safety assessment

Half-life for hydrolysis:

1 yr

at the temperature of:

50 °C

Additional information

EU Method C.7. – The hydrolysis of the test item as a function of pH was determined using a procedure designed to be compatible with Method C.7., Degradation — Abiotic Degradation: Hydrolysis as a Function of pH, of Commission Regulation (EC) No 440/2008 of 30 May 2008.

Sterile buffer solutions at pH’s 4.0, 7.0 and 9.0 were prepared, passed through a 0.2 µm membrane filter to sterilise and subjected to ultrasonication and degassing with nitrogen to minimise dissolved oxygen.  Stock solutions of test item were prepared at a nominal concentration of 5 mg/L in the three buffer solutions; a 1% co-solvent of acetonitrile was used to aid solubility.  The stock solutions were split into individual glass vessels, sealed with minimal headspace, for each data point.  These sample solutions were shielded from light whilst maintained at the test temperature.  Sample solutions at pH 4, 7 and 9 were maintained at 50.0 ± 0.5 °C for a period of 120 hours.

The test item achieved less than 10% hydrolysis after 5 days at 50 °C at pH 4, 7 & 9, equivalent to half-life > 1 year at 25 °C.  The concentration of each solution did not exceed the lesser of 0.01 mol/L or half the water solubility.  The pH of all the test solutions remained stable throughout testing (< ±0.1 pH unit) of the target pH 4, 7 and 9.