N,N,N',N'-tetramethylethylenediamine

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2018-02-21 to 2018-08-28

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

Deviations:

yes

Remarks:

None of the deviations were considered to have impacted the overall integrity of the study or the interpretation of the study results and conclusions.

Qualifier:

according to guideline

Guideline:

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

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.2120 (Hydrolysis of Parent and Degradates as a Function of pH at 25°C)

Principles of method if other than guideline:

N/A

GLP compliance:

yes

Specific details on test material used for the study:

Identity: TMEDA, termed ATMEDAHP in the report
Batch number: 17F-1068310

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

The concentration of the test item in the test samples was determined immediately after preparation (t=0) and after 5 days. The samples taken at t=5 days were cooled to room temperature using running tap water.

Buffers:

Acetate buffer pH 4, 0.01 M: Solution of 16.7% 0.01 M sodium acetate in water and 83.3% 0.01 M acetic acid in water. Buffer contained 0.0009% (w/v) sodium azide.
Phosphate buffer pH 7, 0.01 M: Solution of 0.01 M potassium di-hydrogenphosphate in water adjusted to pH 7 using 1N sodium hydroxide. Buffer contained 0.0009% (w/v) sodium azide.
Borate buffer pH 9, 0.01 M: Solution of 0.01 M boric acid in water and 0.01 M potassium chloride in water adjusted to pH 9 using 1N sodium hydroxide. Buffer contained 0.0009% (w/v) sodium azide.

Estimation method (if used):

N/A

Details on test conditions:

The test item was spiked to the buffer solutions at a target concentration of 2.00 mg/L using a spiking solution in water. Each solution was filter-sterilised through a 0.2 μm FP 30/0.2 CA-S filter (Whatman, Dassel, Germany) and transferred into a sterile vessel. To exclude oxygen, nitrogen gas was purged through the solution for 5 minutes. For each sampling time, duplicate sterile vessels under vacuum were filled with 6 mL test solution and placed in the dark in a temperature controlled environment at 50.1°C ± 0.1°C.
The spiking volume was <1% of the sample volume. Nominal concentrations were not corrected for the spiking volume.
Blank buffer solutions containing a similar content of blank spiking solution were treated similarly as the test samples and analysed at t=0.
The pH of each of the test solutions (except for the blanks) was determined at each sampling time.

Stock Solutions:
Stock solutions of the test item were prepared in water at concentrations of 1000 and 2000 mg/L.

Calibration Solutions:
Six calibration solutions in the concentration range of 0.08 – 5 mg/L were prepared from two stock solutions. Each calibration solution was buffer in pH 4, pH 7 or pH 9 buffer, as applicable.

Sample Injections:
Calibration solutions were injected in duplicate. Test samples were analysed by single injection.

Duration:

5 d

pH:

4

Temp.:

25 °C

Initial conc. measured:

>= 2.58 - <= 2.59 mg/L

Duration:

5 d

pH:

7

Temp.:

25 °C

Initial conc. measured:

>= 2.28 - <= 2.29 mg/L

Duration:

5 d

pH:

9

Temp.:

25 °C

Initial conc. measured:

>= 2.21 - <= 2.22 mg/L

Number of replicates:

Two replicates per buffer (i.e. pH 4, pH 7 and pH 9) were tested.

Positive controls:

not specified

Negative controls:

not specified

Statistical methods:

Six calibration solutions in the concentration range of 0.08 – 5 mg/L were constructed, two curves for calibration solution in buffers for pH 4, pH 7 and pH 9.

All of the constructed calibration curves (i.e. for pH 4, pH 7 and pH 9) showed that there was a quadratic relationship between response and test item concentration in the range of 0.08 – 5.00 mg/L (in end solution). The coefficients of correlation (r) were >0.99 and the back calculated accuracies of the data points were in the range 85-115%, thus the calibration lines were accepted in all cases.

Preliminary study:

At pH 4, 7 and 9 the degree of hydrolysis observed was <10% after 5 days, demonstrating that the half-life time of the test item at 25°C is >1 year. According to the guideline, no further tests were therefore required. No test item was detected in the blank buffer solutions.

Test performance:

The rate of hydrolysis of the test item as a function of pH was determined at pH values normally found in the environment (pH 4-9).

Transformation products:

no

Details on hydrolysis and appearance of transformation product(s):

N/A

% Recovery:

129

pH:

4

Temp.:

25 °C

Duration:

5 d

Remarks on result:

hydrolytically stable based on preliminary test

% Recovery:

114

pH:

7

Temp.:

25 °C

Duration:

5 d

Remarks on result:

hydrolytically stable based on preliminary test

% Recovery:

111

pH:

9

Temp.:

25 °C

Duration:

5 d

Remarks on result:

hydrolytically stable based on preliminary test

pH:

4

Temp.:

25 °C

DT50:

> 1 yr

Remarks on result:

hydrolytically stable based on preliminary test

pH:

7

Temp.:

25 °C

DT50:

> 1 yr

Remarks on result:

hydrolytically stable based on preliminary test

pH:

9

Temp.:

25 °C

DT50:

> 1 yr

Remarks on result:

hydrolytically stable based on preliminary test

Other kinetic parameters:

N/A

Details on results:

The degree of hydrolysis observed at pH 4, 7 and 9 in the preliminary test (Tier 1) was <10% after 5 days, demonstrating that the half-life time of the test item at 25°C is >1 year. According to the guideline, no further tests were therefore required. No test item was detected in the blank buffer solutions.

Although the calibration curves were prepared in the same matrix as the samples, the mean recovery of the test item in the buffer solutions at t=0 fell outside the criterion range of 70-110% for non-labelled chemicals. Because hydrolysis is calculated using the relative concentration, the high recoveries of the test item do not have any effect on the outcome of the study. Furthermore the recoveries of the test item in the pH 7 and pH 9 buffer solutions were accepted as the criterion range of 70-110% was only slightly exceeded.

Results with reference substance:

N/A

Hydrolysis of the Test Item at pH 4, pH 7 and pH 9

 

pH code	Sampling time	Analysed concentration [mg/L]	Degree of hydrolysis [%]		pH
			Individual	Mean
pH 4	0 hours	2.58			4.0
		2.59			4.0
	5 days	2.67	-3.3	0.17	4.0
		2.49	3.6		4.0
pH 7	0 hours	2.28			7.0
		2.29			7.0
	5 days	2.18	4.4	5.1	7.0
		2.15	5.7		7.0
pH 9	0 hours	2.21			9.0
		2.22			9.0
	5 days	2.15	3.1	3.0	9.0
		2.15	2.8		9.0

 

Recoveries

 

pH code	Nominal concentration	Analysed concentration [mg/L]	Recovery [%]
			Individual	Mean
pH 4	2.00	2.58	129	129
	2.00	2.59	130
pH 7	2.00	2.28	114	114
	2.00	2.29	114
pH 9	2.00	2.21	110	111
	2.00	2.22	111

  

Validity criteria fulfilled:

yes

Conclusions:

The preliminary test (Tier 1) was performed for the determination of the rate of hydrolysis of TMEDA (N,N,N’,N’-tetramethylethylenediamine) at pH values normally found in the environment (pH 4-9). At each pH value <10% hydrolysis of the test item was observed after 5 days, demonstrating that the half-life time of the test item at 25°C is >1 year. According to the guideline, performance of the main study (Tier 2) was not required.

Executive summary:

The hydrolytic stability of TMEDA (N,N,N’,N’-tetramethylethylenediamine) was determined at pH values normally found in the environment (pH 4-9) via a GLP-compliant test performed according to OECD Guideline 111 (Hydrolysis as a function of pH).

  

Quantitative analysis of the test item in the study was performed according to a validated analytical method using ultra-performance liquid chromatographic with mass spectrometric detection (UPLC-MS). The test item was spiked to the buffer solutions (pH 4, pH 7 and pH 9) at a target concentration of 2.00 mg/L using a spiking solution in water. Test samples were taken immediately after preparation (t=0) and after 5 days and the concentration of the test item in the test samples was determined.

  

Results from the preliminary test (Tier 1) showed that at each pH value <10% hydrolysis of the test item was observed after 5 days, thereby demonstrating that the half-life time of the test item at 25°C is >1 year. According to the guideline, performance of the main study (Tier 2) was not required and it is concluded that TMEDA is hydrolytically stable.

Description of key information

The hydrolytic stability of TMEDA (N,N,N’,N’-tetramethylethylenediamine) was determined at pH values normally found in the environment (pH 4-9) via a GLP-compliant test performed according to OECD Guideline 111 (Hydrolysis as a function of pH).

  

Quantitative analysis of the test item in the study was performed according to a validated analytical method using ultra-performance liquid chromatographic with mass spectrometric detection (UPLC-MS). The test item was spiked to the buffer solutions (pH 4, pH 7 and pH 9) at a target concentration of 2.00 mg/L using a spiking solution in water. Test samples were taken immediately after preparation (t=0) and after 5 days and the concentration of the test item in the test samples was determined.

  

Results from the preliminary test (Tier 1) showed that at each pH value <10% hydrolysis of the test item was observed after 5 days, thereby demonstrating that the half-life time of the test item at 25°C is >1 year. According to the guideline, performance of the main study (Tier 2) was not required and it is concluded that TMEDA is hydrolytically stable.

Key value for chemical safety assessment

Half-life for hydrolysis:

1 yr

at the temperature of:

25 °C