[1,1'-Biphenyl]-2,2'-diol, 3,3'-bis(1,1-dimethylethyl)-5,5'-dimethoxy-

Hydrolysis

Administrative data

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

between 08 January 2009 and 01 April 2009.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study conducted to GLP and in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do no effect the quality of the relevant results.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2009

Report date:

2009

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Date of inspection: 19/08/08 Date of Signature: 04/03/09

Test material

Test material information

Constituent 1

Reference substance name:

L17_Precursor

IUPAC Name:

L17_Precursor

Constituent 2

Reference substance name:

6,6'-di-tert-butyl-4,4'-dimethoxy-[1,1'-biphenyl]-2,2'-diol

EC Number:

604-200-4

Cas Number:

14078-41-2

Molecular formula:

C22 H30 O4

IUPAC Name:

6,6'-di-tert-butyl-4,4'-dimethoxy-[1,1'-biphenyl]-2,2'-diol

Details on test material:

Sponsor's identification : L17_Precursor
Description : pale yellow powder
Chemical name : 5,5-dimethoxy-3,3’-di-tert-butyl-2,2’-biphenol
CAS number : 14078-41-2
Purity : 93.4%
Batch number : DALA046312
Date received : 11 November 2008
Storage conditions : room temperature in the dark

Radiolabelling:

no

Study design

Analytical monitoring:

yes

Details on sampling:

Preparation:
The buffer solutions were 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 degassing with nitrogen to minimise dissolved oxygen content.

Preparation of samples:
Sample solutions were prepared in stoppered glass flasks at a nominal concentration of 1 x 10-4 g/l in the three buffer solutions. A 1% co-solvent of acetone was used to aid solubility. These were split into individual vessels for each data point.
The solutions were shielded from light whilst maintained at the test temperature.

Preliminary test:
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 incubator at various times and the pH of each solution recorded. The concentration of the sample solution was determined by gas chromatography (GC).

Samples:
An aliquot (100 ml) of each sample was extracted with three portions (3 x 25 ml) of dichloromethane which had been used to rinse the sample vessel and aided by ~5 g of sodium chloride, each extract being filtered through anhydrous sodium sulphate. The combined extracts were evaporated to dryness and the residue re-dissolved in acetone (4 ml).

Standards:
Duplicate standard solutions of test material were prepared in acetone at a nominal concentration of 2.5 mg/l.

Matrix blanks
Acetone and 100 ml of the buffer solutions extracted as per the samples.

Buffers:

Buffer solutions:
(pH) Components Concentration
(mol dm-3)
4 Potassium hydrogen phthalate 0.005
7 Disodium hydrogen orthophosphate (anhydrous) 0.003
Potassium dihydrogen orthophosphate 0.002
Sodium chloride 0.002
9 Disodium tetraborate 0.001
Sodium chloride 0.002
The buffer solutions were 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 degassing with nitrogen to minimise dissolved oxygen content.

Estimation method (if used):

Calculation:
The mean peak area of each standard was corrected to a nominal concentration of 2.5 mg/l and the mean value taken.
The concentration of the sample solutions (g/l) was calculated using the equation below:

Cspl= Pspl/Pstdx Cstdx D x 1/1000

where:
Cspl = sample concentration (g/l)
Pspl = mean peak area of sample solution
Pstd = mean peak area of standard solution, corrected to nominal standard concentration
Cstd = nominal standard concentration (2.5 mg/l)
D = sample dilution factor (0.04)

Duration of test

Duration of test 1

Duration:

120 h

pH:

4

Initial conc. measured:

10 g/L

Duration of test 2

Duration:

120 h

pH:

7

Initial conc. measured:

10 g/L

Duration of test 3

Duration:

120 h

pH:

9

Initial conc. measured:

10 g/L

Number of replicates:

Duplicate aliquots (A and B) of sample solution were diluted by a factor of 100 using glass double-distilled water.

Positive controls:

no

Negative controls:

no

Statistical methods:

Not specified

Results and discussion

Preliminary study:

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

Test performance:

The linearity of the detector response with respect to concentration was assessed over the nominal concentration range of 0 to 20 mg/l. This was satisfactory with a correlation coefficient of 0.998 being obtained.

pH Recovery range (%) Mean recovery (%)
4 84.2 to 101 90.9
7 84.4 to 98.1 92.6
9 86.4 to 100 93.2

Transformation products:

not specified

Identity of transformation products

Reference

Reference substance name:

Unnamed

IUPAC name:

No significant Hydrolysis observed over all pH levels. Therefore, no degradation products recorded.

Identifier:

other:

Identity:

No significant Hydrolysis observed over all pH levels. Therefore, no degradation products recorded.

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

Approximately 10% hydrolysis after 5 days at 50°C, equivalent to a half-life greater than 1 year at 25°C. at pH 4, 7 and 9

Dissipation DT50 of parent compound

Dissipation DT50 of parent compound 1

pH:

4

Temp.:

25 °C

DT50:

> 1 yr

Type:

other: estimated result

Dissipation DT50 of parent compound 2

pH:

7

Temp.:

25 °C

DT50:

> 1 yr

Type:

other: estimated result

Dissipation DT50 of parent compound 3

pH:

9

Temp.:

25 °C

DT50:

> 1 yr

Type:

other: estimated result

Other kinetic parameters:

None.

Details on results:

At pH 4, 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.

Any other information on results incl. tables

Preliminary test/Tier 1:

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

Solution	MeanArea
Standard 2.94 mg/l	28.099
Standard 2.62 mg/l	25.072
Initial Sample A, pH 4	44.896
Initial Sample B, pH 4	12.995
Initial Sample A, pH 7	18.563
Initial Sample B, pH 7	20.527
Initial Sample A, pH 9	14.635
Initial Sample B, pH 9	10.890
Standard 2.94 mg/l	28.748
Standard 2.62 mg/l	25.011
24 Hour Sample A, pH 4	19.556
24 Hour Sample B, pH 4	23.927
24 Hour Sample A, pH 7	19.645
24 Hour Sample B, pH 7	21.501
24 Hour Sample A, pH 9	15.467
24 Hour Sample B, pH 9	20.206
Standard 2.48 mg/l	21.970
Standard 2.53 mg/l	22.629
120 Hour Sample A, pH 4	20.971
120 Hour Sample B, pH 4	20.223
120 Hour Sample A, pH 7	19.214
120 Hour Sample B, pH 7	20.872
120 Hour Sample A, pH 9	20.500
120 Hour Sample B, pH 9	10.229

 

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

     pH 4 at 50.0 ± 0.5ºC

Time (Hours)	Concentration (g/l)		% of as weighed in
	A	B	A	B
0	1.88 x 10^-4	5.44 x 10^-5	186	54.0
24	8.10 x 10^-5	9.91 x 10^-5	80.4	98.4
120	9.41 x 10^-5	9.08 x 10^-5	93.4	90.1

Result:           Approximately10% hydrolysis after 5 days at 50°C, equivalent to a half-life greater than 1 year at 25°C.

 pH 7 at 50.0 ± 0.5ºC

Time (Hours)	Concentration (g/l)		% of as weighed in
	A	B	A	B
0	7.77 x 10^-5	8.59 x 10^-5	77.1	85.3
24	8.14 x 10^-5	8.90 x 10^-5	80.8	88.4
120	8.62 x 10^-5	9.37 x 10^-5	85.6	93.0

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

    pH 9 at 50.0 ± 0.5ºC

Time (Hours)	Concentration (g/l)		% of as weighed in
	A	B	A	B
0	6.12 x 10^-5	4.56 x 10^-5	60.8	45.2
24	6.41 x 10^-5	8.37 x 10^-5	63.6	83.1
120	9.20 x 10^-5	4.59 x 10^-5	91.4	45.6*

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

*The assessment of stability at 120 hours was not based on this sample. See the discussion below.

Discussion:

Due to problems encountered during testing, the test sample results were erratic. Investigative work showed that test material adsorbed to the test vessel’s surface; as test material was detected in dichloromethane washes of the test vessels. The test vessel washing procedure was used for all samples during the test and involved rinsing with the dichloromethane before being used for sample extraction. The test sample results may still have been more variable compared to the recoveries due to the test samples being prepared as a stock solution and sub-sampled exposing the test material to a greater surface area to adsorb to; compared to the recovery sample preparation method.

It has been considered, based predominantly on the 120 hour results, that the test material did not undergo significant hydrolysis at 50°C in all pHs. The 120 hour results did approximate to the ‘as weighed in’ concentration (besides pH 9 sample B) if the recovery percentage was taken into account. The results also showed there was no indication of a decrease in concentration in the 96 hour period from the 24 hour samples to the 120 hour samples, again suggesting the test material was stable. The reason for the high result for pH 4 sample A was uncertain, but may have been due to a co-eluting peak.

The functional groups within the test material were phenyl alcohols and ethers. Neither of these was considered to be hydrolytically unstable under environmentally relevant conditions.

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

As the test material was determined to be hydrolytically stable under acidic conditions (t_½ > 1 year at 25°C) no additional testing was performed at pH 1.2, 37.0 ± 0.5°C.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The estimated half-life at 25°C of the test material are shown in the table below:

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

Executive summary:

Method

The determination was carried out using Method C7 of Commission Directive 92/69/EEC (which constitutes Annex V of Council Directive 67/548/EEC), Method 111 of the OECD Guidelines for Testing of Chemicals, 13 April 2004.

Conclusion.

The estimated half-life at 25°C of the test material are shown as follows:

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