Registration Dossier

Administrative data

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
02, 11, 16 March 2004
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: 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 relevant results.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2004
Report Date:
2004

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Remarks:
(Date of inspection: 02 December 2002 Date of signature: 13 February 2003)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): TIPX
- Substance type: Colourless liquid.
- Physical state: Liquid.
- Lot/batch No.: 042028.
- Storage condition of test material: Approximately 4ºC in the dark.
Radiolabelling:
no

Study design

Analytical monitoring:
yes
Details on sampling:
- Sampling method: Aliquots of the sample solutions were taken from the flasks at various times and the pH of each solution recorded.

- Sample storage conditions before analysis: The solutions were shielded from light whilst maintained at the test temperature.
Buffers:
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. Specification of buffer solutions can be found in Table 2.
Estimation method (if used):
Not applicable.
Details on test conditions:
TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: Glass flasks, volume unspecified.

- If no traps were used, is the test system closed/open: closed.


OTHER TEST CONDITIONS
- Stability check: From information provided by the Sponsor and previous experience of similar types of silicon containing compound it was expected that the test material would be rapidly hydrolysable. The hydrolysis observed was in fact so rapid that at the concentration levels required for the hydrolysis test no test material remained by the time the initial samples could be extracted.
To obtain further confirmatory information, a stability check was performed by preparing a sample at approximately 1 g/l in acetonitrile: water (50:50 v/v). Aliquots were taken initially and at 10 minute intervals up to 70 minutes, which were diluted by a factor of 10 with acetone and analysed by GC (using the parameters indicated in section 10.1.1.4, with the exception that a flame-ionisation detector was used in place of a mass-selective detector). The test was performed under safety lighting to avoid photolysis, and at ambient (room) temperature.
Duration of testopen allclose all
Duration:
2.4 h
pH:
4
Temp.:
50 °C
Initial conc. measured:
< 0.147 µg/L
Duration:
2.4 h
pH:
7
Temp.:
50 °C
Initial conc. measured:
< 0.126 µg/L
Duration:
2.4 h
pH:
9
Temp.:
50 °C
Initial conc. measured:
< 0.137 µg/L
Number of replicates:
Duplicate for each sample, both for the sample and standard.
Positive controls:
no
Negative controls:
no

Results and discussion

Preliminary study:
See Table 3 for the mean peak heights relating to the standard and sample solutions.
Test performance:
(As recovery) The rapid hydrolysis of the test material made recovery very difficult. Concentrations have not been corrected for recovery of analysis, as no test material was detected in the sample solutions.
Transformation products:
not specified
Details on hydrolysis and appearance of transformation product(s):
Not reported.

Total recovery of test substance (in %)open allclose all
% Recovery:
>= 7.63 - <= 9.03
% Recovery:
>= 8.14 - <= 33.4
Dissipation half-life of parent compoundopen allclose all
pH:
4
Temp.:
25 °C
Half-life:
< 24 h
pH:
7
Temp.:
25 °C
Half-life:
< 24 h
pH:
9
Temp.:
25 °C
Half-life:
< 24 h
Other kinetic parameters:
Not reported.
Details on results:
HYDROLYSIS
Greater than 50% hydrolysis after 2.4 hours at 50°C, equivalent to a half-life of less than 1 day at 25°C, at all conditions tested. See the results in Table 4 for she test material concentrations at the given time points.

STABILITY
Only 27.6% of the test material remained after 60 minutes even when a high proportion of solvent was present, confirming the rapid hydrolysis of the test material in aqueous media. It is estimated that the test material will undergo a simple ester-type hydrolysis reaction, giving triisopropyl silanol and acrylic acid as hydrolysis products.

Any other information on results incl. tables

Table 1 Recovery data

Nominal concentration

(mg/l)

Recovery range (%)

Mean recovery (%)

2.00 x 10-2

7.63 to 9.03

8.46

1.10

8.14 to 33.4

18.4

Table 2 Specification of buffer solutions

Buffer solution

Components

Concentration

(mmol dm-3)

4

Potassium hydrogen phthalate

5.00

7

Disodium hydrogen orthophosphate (anhydrous)

3.00

Potassium dihydrogen orthophosphate

2.00

Sodium chloride

2.00

9

Disodium tetraborate

1.00

Sodium chloride

2.00

Table 3 Results of the preliminary test

Solution

MeanHeight

Standard 2.21 mg/l

2.662 x 104

Standard 2.01 mg/l

2.384 x 104

Initial Sample A, pH 4

<176.000*

Initial Sample B, pH 4

<176.000*

2.4 Hour Sample A, pH 4

<176.000*

2.4 Hour Sample B, pH 4

<176.000*

Standard 2.01 mg/l

2.592 x 104

Standard 2.08 mg/l

2.756 x 104

Initial Sample A, pH 7

<164.000*

Initial Sample B, pH 7

<164.000*

2.4 Hour Sample A, pH 7

<164.000*

2.4 Hour Sample B, pH 7

<164.000*

Standard 2.03 mg/l

2.464 x 104

Standard 2.01 mg/l

2.723 x 104

Initial Sample A, pH 9

<176.000*

Initial Sample B, pH 9

<176.000*

2.4 Hour Sample A, pH 9

<176.000*

2.4 Hour Sample B, pH 9

<176.000*

*Limit value used as no test material was detected in the samples. This value was calculated from 4 times the baseline noise at the retention time of the test material for each run.

Table 4 Results of Hydrolysis

 

pH 4 at 50.0 ± 0.5ºC

Time (Hours)

0

2.4

Concentration (g/l)

<1.47 x 10-7

<1.47 x 10-7

% of fortification

<0.700

<0.700

  

pH 7 at 50.0 ± 0.5ºC

Time (Hours)

0

2.4

Concentration (g/l)

<1.26 x 10-7

<1.26 x 10-7

% of fortification

<0.619

<0.619

  

pH 9 at 50.0 ± 0.5ºC

Time (Hours)

0

2.4

Concentration (g/l)

<1.37 x 10-7

<1.37 x 10-7

% of fortification

<0.678

<0.678

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The estimated half-life at 25°C of the test material is less than 24 hours at pH 4, 7 and 9.
Executive summary:

Assessment of hydrolytic stability was carried out using Method C7 of Commission Directive 92/69/EEC. Greater than 50% hydrolysis after 2.4 hours at 50°C, equivalent to a half-life of less than 1 day at 25°C, at all conditions tested. The estimated half-life at 25°C of the test material is less than 24 hours at pH 4, 7 and 9.