1,1,3,3-tetramethylbutyl hydroperoxide

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Testing was conducted between 30 November 2011 and 02 June 2012.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results. The study report was conclusive, done to a valid guideline and the study was conducted under GLP conditions.

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

Deviations:

no

GLP compliance:

yes

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

The buffer solutions were diluted to 5% using reverse osmosis water and filtered through a 0.2 µm membrane filter to ensure they were sterile before commencement of the test. Also these solutions were subjected to ultrasonication and dissolved oxygen was removed from the solution by sparging with nitrogen.

Preparation of samples
Sample solutions were prepared in stoppered glass flasks at a nominal concentration of 1 g/l in the three buffer solutions. A 1% co-solvent of acetonitrile was used to aid solubility.
The test solutions were split into individual vessels for each data point.
The solutions were shielded from light whilst maintained at the test temperature.

Preliminary test/Tier 1
Sample solutions at pH 4, 7 and 9 were maintained at 50.0 ± 0.5°C for a period of 120 hours.

Analysis of sample solutions
The sample solutions were taken from the water bath at various times and the pH of each solution recorded.
The concentration of the sample solution was determined by high performance liquid chromatography (HPLC).
Samples

Duplicate aliquots (A and B) of sample solution were diluted by a factor of 2 using acetonitrile.

Standards
Duplicate standard solutions of test item were prepared in acetonitrile:relevant buffer solution (1:1 v/v) at a nominal concentration of 500 mg/l.

Matrix blanks
Acetonitrile:relevant buffer solution (1:1 v/v)

Buffers:

Buffer solution
(pH) Components Concentration (mol/litre)
4 Potassium hydrogen phthalate 0.05
7 Disodium hydrogen orthophosphate (anhydrous) 0.03
Potassium dihydrogen orthophosphate 0.02
Sodium chloride 0.02
9 Disodium tetraborate 0.01
Sodium chloride 0.02

The buffer solutions were diluted to 5% using reverse osmosis water and filtered through a 0.2 µm membrane filter to ensure they were sterile before commencement of the test. Also these solutions were subjected to ultrasonication and dissolved oxygen was removed from the solution by sparging with nitrogen.

Estimation method (if used):

Not used.

Details on test conditions:

Refer to details on sampling and analytical methods.

Duration:

120 h

pH:

4

Initial conc. measured:

0.949 other: g/l - Sample A

Duration:

120 h

pH:

4

Initial conc. measured:

0.941 other: g/l - Sample B

Duration:

120 h

pH:

7

Initial conc. measured:

0.997 other: g/l - Sample A

Duration:

120 h

pH:

7

Initial conc. measured:

0.934 other: g/l - Sample B

Duration:

120 h

pH:

9

Initial conc. measured:

0.987 other: g/l - Sample A

Duration:

120 h

pH:

9

Initial conc. measured:

0.925 other: g/l Sample B

Number of replicates:

Duplicate aliquots (A and B) of sample solution were diluted by a factor of 2 using acetonitrile.

Positive controls:

no

Negative controls:

no

Statistical methods:

Not specified.

Preliminary study:

The mean peak areas relating to the standard and sample solutions are shown in table 6.2 (please see remarks on results including tables and figures section).

The test item concentrations at the given time points are shown in tables 6.3 - 6.5 incl. (please see remarks on results including tables and figures section).

Test performance:

Validation
The linearity of the detector response with respect to concentration was assessed over the nominal concentration ranges of 20.2 to 759 mg/l for the pH 4 buffer matrix, 23.1 to 868 mg/l for the pH 7 buffer matrix and 22.3 to 837 mg/l for the pH 9 buffer matrix. These were satisfactory with correlation coefficients of 1.000 being obtained for each matrix.

Transformation products:

not specified

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

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

Key result

pH:

4

Temp.:

25 °C

DT50:

> 1 yr

Key result

pH:

7

Temp.:

25 °C

DT50:

> 1 yr

Key result

pH:

9

Temp.:

25 °C

DT50:

> 1 yr

Other kinetic parameters:

None.

Details on results:

At pH4, 7 and 9 there was less than 10% hydrolysis after 5 days at 50°C, equivalent to a half-life greater than 1 year at 25°C.

Results

Preliminary test/Tier 1

The mean peak areas relating to the standard and sample solutions are shown in the following table:

Table 6.2

Solution	Mean Peak Area
Standard 531 mg/l	1.1839 x 10^7
Standard 503 mg/l	1.1241 x 10^7
Initial Sample A, pH 4	1.0595 x 10^7
Initial Sample B, pH 4	1.0506 x 10^7
Standard 531 mg/l	1.1961 x 10^7
Standard 503 mg/l	1.1302 x 10^7
Initial Sample A, pH 7	1.1218 x 10^7
Initial Sample B, pH 7	1.0510 x 10^7
Standard 531 mg/l	1.1966 x 10^7
Standard 503 mg/l	1.1305 x 10^7
Initial Sample A, pH 9	1.1110 x 10^7
Initial Sample B, pH 9	1.0417 x 10^7
Standard 529 mg/l	1.1836 x 10^7
Standard 549 mg/l	1.2353 x 10^7
24-Hour Sample A, pH 4	1.0367 x 10^7
24-Hour Sample B, pH 4	1.0812 x 10^7
Standard 529 mg/l	1.1933 x 10^7
Standard 549 mg/l	1.2406 x 10^7
24-Hour Sample A, pH 7	1.0863 x 10^7
24-Hour Sample B, pH 7	1.0800 x 10^7
Standard 529 mg/l	1.1983 x 10^7
Standard 549 mg/l	1.2364 x 10^7
24-Hour Sample A, pH 9	1.0368 x 10^7
24-Hour Sample B, pH 9	1.0327 x 10^7

Standard 533 mg/l	1.1384 x 10^7
Standard 639 mg/l	1.3831 x 10^7
120-Hour Sample A, pH 4	1.0314 x 10^7
120-Hour Sample B, pH 4	1.0311 x 10^7
Standard 533 mg/l	1.1253 x 10^7
Standard 639 mg/l	1.3774 x 10^7
120-Hour Sample A, pH 7	1.0656 x 10^7
120-Hour Sample B, pH 7	1.0783 x 10^7
Standard 533 mg/l	1.1356 x 10^7
Standard 639 mg/l	1.3771 x 10^7
120-Hour Sample A, pH 9	1.0052 x 10^7
120-Hour Sample B, pH 9	9.8957 x 10^6

 

The test item concentrations at the given time points are shown in the following tables:

Table 6.3      pH 4 at 50.0 ± 0.5ºC

Time (Hours)	Mean Concentration (g/l)		% of mean initial concentration (g/l)
	A	B	A	B
0	0.949	0.941	-	-
24	0.924	0.963	97.8	102
120	0.959	0.959	102	102

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

Table 6.4      pH 7 at 50.0 ± 0.5ºC

Time (Hours)	Mean Concentration (g/l)		% of mean initial concentration (g/l)
	A	B	A	B
0	0.997	0.934	-	-
24	0.962	0.956	99.6	99.1
120	0.999	1.01	103	105

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

Table 6.5      pH 9 at 50.0 ± 0.5ºC

Time (Hours)	Mean Concentration (g/l)		% of mean initial concentration (g/l)
	A	B	A	B
0	0.987	0.925	-	-
24	0.918	0.914	96.0	95.6
120	0.938	0.924	98.1	96.6

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

Validity criteria fulfilled:

yes

Conclusions:

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

Executive summary:

Method

The determination was carried out using a procedure designed to be compatible with Method 111 of the OECD Guidelines for Testing of Chemicals, 13 April 2004.

Conclusion

The estimated half-lives at 25°C of the test item are shown in the following table:

Table 6.6

pH	Estimated half-life at 25°C
4	>1 year
7	>1 year
9	>1 year

Description of key information

The results of an OECD 111 test showed that the estimated half-life at 25°C of 1,1,3,3-tetramethylbutyl hydroperoxide at pH 4, 7 and 9 is greater than 1 year.

Key value for chemical safety assessment

Half-life for hydrolysis:

1 yr

at the temperature of:

50 °C

Additional information

One study is available conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines (OECD 111) and/or minor methodological deficiencies, which do not affect the quality of the relevant results. The study report was conclusive, done to a valid guideline and the study was conducted under GLP conditions. The estimated half-life at 25°C of 1,1,3,3-tetramethylbutyl hydroperoxide at pH 4, 7 and 9 is greater than 1 year.