1,4-diisopropylbenzene

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2011

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

The study was conducted using a documented method and in compliance with GLP.

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

Stock solutions were prepared in flasks at a nominal concentration of 2 x 10"3 g/L in the three buffer solutions. A 5 % co-solvent of tetrahydrofuran was used to aid dissolution.
The stock solutions were split into individual vessels for each data point. The solutions were shielded from light whilst maintained at the test temperature.

Buffers:

- pH: 4, 7 and 9
- composition of buffer, type and final molarity of buffer:
pH 4: Citiric acid (3.1 mmol dm-3), sodium cloride (2.2 mmol dm-3), sodium hydroxide (3.4 mmol dm-3)
pH 7: Disodium hydrogen orthophosphate (anhydrous) (1.5 mmol dm-3), pottasium dihydrogen orthophosphate (1 mmol dm-3), sodium chloride (1 mmol dm-3)
pH 9: Disodium tetraborate (0.5 mmol dm-3), sodium cloride (1 mmol dm-3)

Number of replicates:

2

Transformation products:

no

% Recovery:

>= 105 - <= 110

St. dev.:

3.535

pH:

4

Temp.:

50 °C

Duration:

72 h

% Recovery:

>= 81 - <= 96

St. dev.:

10.748

pH:

4

Temp.:

50 °C

Duration:

120 h

% Recovery:

>= 105 - <= 106

St. dev.:

0.707

pH:

7

Temp.:

50 °C

Duration:

72 h

% Recovery:

>= 100 - <= 107

St. dev.:

4.95

pH:

7

Temp.:

50 °C

Duration:

120 h

% Recovery:

>= 110 - <= 123

St. dev.:

9.192

pH:

9

Temp.:

50 °C

Duration:

72 h

% Recovery:

>= 86.1 - <= 118

St. dev.:

22.557

pH:

9

Temp.:

50 °C

Duration:

120 h

Temp.:

25 °C

DT50:

> 1 yr

Validation

The linearity of the detector response with respect to concentration was assessed over the nominal concentration range of 0.5 to 20 mg/L. This was satisfactory with a correlation coefficient (r2) of 1.000 being obtained. Recovery of analysis of the sample procedure was assessed and proved adequate for the test. At a nominal concentration of 2 mg/L, a mean percentage recovery of 79.4 % was obtained (range 77.4 to 80.3 %). Concentrations have not been corrected for recovery of analysis.

 

Discussion

No significant peaks were observed at the approximate retention time of the test item on analysis of any matrix blank solutions. An initial attempt at the test had shown that a very small amount of the test item remained after 72 hours for all three pH's. From the chemical structure and physical parameters it was considered that the reduction in test item concentration was not due to hydrolysis but volatilisation. The test item, being a hydrocarbon, had no hydrolysable groups. The test was repeated with a higher percentage of co-solvent to help retain the test item in solution and with no headspace in the sealed sample vessels to minimalise the loss by volatilisation. Although after 120 hours samples pH 4A and pH 9B had reduced by more than 10 % compared to their averaged initial samples, it was considered that this was due to volatilisation as the sample vessels were later found to have a cracked base. It can even be seen with all samples that they were significantly lower than their "as weighed in concentration" and was also seen in the first attempt at the test. Overall, it was considered that the test item did not hydrolyse and had an estimated half-life of greater than 1 year at 25 °C for pH 4, pH 7 and pH 9.

Validity criteria fulfilled:

yes

Conclusions:

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

Executive summary:

The estimated half-life at 25 °C of the test item at pH 4, pH 7 and pH 9 was shown to be greater than 1 year. Assessment of hydrolytic stability was carried out using a procedure designed to be compatible with Method C7 Abiotic Degradation, Hydrolysis as a Function of pH of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 111 of the OECD Guidelines for Testing of Chemicals, 13 April 2004.

Description of key information

Assessment of hydrolytic stability was carried out using a procedure designed to be compatible with Method C7 Abiotic Degradation, Hydrolysis as a Function of pH of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 111 of the OECD Guidelines for Testing of Chemicals, 13 April 2004.

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

Key value for chemical safety assessment

Half-life for hydrolysis:

1 yr

at the temperature of:

25 °C

Additional information

Assessment of hydrolytic stability was carried out using a procedure designed to be compatible with Method C7 Abiotic Degradation, Hydrolysis as a Function of pH of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 111 of the OECD Guidelines for Testing of Chemicals, 13 April 2004.

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