Registration Dossier

Administrative data

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Testing was conducted between 08 December 2011 and 24 April 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.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2012
Report Date:
2012

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
Deviations:
no
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Description:amber coloured viscous liquid
Purity: 100% (based on UVCB composition)
Expiry date: 01 December 2012
Date received: 01 December 2011
Storage conditions: room temperature, in the dark
Radiolabelling:
no

Study design

Analytical monitoring:
yes
Details on sampling:
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 1.5 x 10-2 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 for pH 4 and a period of 381 hours at pH 7 and pH 9.

Additional testing directly at 25°C
Results from the Preliminary test/Tier 1 showed it was necessary to undertake further testing at pH 7, with solutions being maintained at 25.0 ± 0.5°C for a period of 768 hours.

Analysis of sample solutions
Duplicate vessels of sample solutions were taken from the waterbaths at each timepoint and the pH of each solution recorded.
The test item concentration of the sample solutions were then determined by high performance liquid chromatography (HPLC).

Samples
An aliquot of each of the duplicate vessels of sample solution (A and B) was diluted by a factor of 2 using methanol.

Standards
Duplicate standard solutions of test item were prepared in methanol: relevant buffer solution (50:50 v/v) at a nominal concentration of 7.5 mg/l for each pH.

Matrix blanks
Methanol: relevant buffer solution (50:50 v/v) for each pH.
Duration of testopen allclose all
Duration:
120 h
pH:
4
Initial conc. measured:
0.152 g/L
Duration:
120
pH:
7
Initial conc. measured:
0.153 g/L
Duration:
120
pH:
9
Initial conc. measured:
0.156 g/L
Positive controls:
no
Negative controls:
no

Results and discussion

Preliminary study:
The mean peak total areas relating to the standard and sample solutions are shown in the table 9.2 please see other information on results including tables section.
Test performance:
Validation
The linearity of the detector response with respect to concentration was assessed over the nominal concentration range of 0 to 10 mg/l. This was satisfactory with a correlation coefficient of 1.000 being obtained for the analysis matrix for all 3 pH’s investigated.
Transformation products:
not specified
Dissipation DT50 of parent compoundopen allclose all
pH:
4
Temp.:
25 °C
DT50:
> 1 yr
pH:
7
Temp.:
25 °C
DT50:
> 1 yr
pH:
9
Temp.:
25 °C
DT50:
> 1 yr
Other kinetic parameters:
None.

Any other information on results incl. tables

Results

 Preliminary test/Tier 1

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

Table 9.2

Solution

Mean Total Peak Area

Standard 7.96 mg/l

1.402 x 107

Standard 8.05 mg/l

1.409 x 107

Initial Sample A, pH 4

1.336 x 107

Initial Sample B, pH 4

1.337 x 107

Standard 7.96 mg/l

1.374 x 107

Standard 8.05 mg/l

1.404 x 107

Initial Sample A, pH 7

1.331 x 107

Initial Sample B, pH 7

1.326 x 107

Standard 7.96 mg/l

1.342 x 107

Standard 8.05 mg/l

1.386 x 107

Initial Sample A, pH 9

1.328 x 107

Initial Sample B, pH 9

1.330 x 107

Standard 7.44 mg/l

1.311 x 107

Standard 8.00 mg/l

1.439 x 107

24 Hour Sample A, pH 4

1.304 x 107

24 Hour Sample B, pH 4

1.335 x 107

Standard 7.44 mg/l

1.314 x 107

Standard 8.00 mg/l

1.424 x 107

24 Hour Sample A, pH 7

1.284 x 107

24 Hour Sample B, pH 7

1.289 x 107

Standard 7.44 mg/l

1.312 x 107

Standard 8.00 mg/l

1.425 x 107

24 Hour Sample A, pH 9

1.309 x 107

24 Hour Sample B, pH 9

1.330 x 107

 

 


Table 9.2 continued

Solution

Mean Total Peak Area

Standard 8.06 mg/l

1.343 x 107

Standard 7.97 mg/l

1.295 x 107

120 Hour Sample A, pH 4

1.186 x 107

120 Hour Sample B, pH 4

1.189 x 107

Standard 8.06 mg/l

1.385 x 107

Standard 7.97 mg/l

1.362 x 107

120 Hour Sample A, pH 7

1.132 x 107

120 Hour Sample B, pH 7

1.149 x 107

Standard 8.06 mg/l

1.366 x 107

Standard 7.97 mg/l

1.354 x 107

120 Hour Sample A, pH 9

1.205 x 107

120 Hour Sample B, pH 9

1.186 x 107

Standard 7.98 mg/l

1.375 x 107

Standard 7.62 mg/l

1.270 x 107

216 Hour Sample A, pH 9

1.154 x 107

216 Hour Sample B, pH 9

1.146 x 107

Standard 7.35 mg/l

1.256 x 107

Standard 7.78 mg/l

1.326 x 107

381 Hour Sample A, pH 7

1.006 x 107

381 Hour Sample B, pH 7

1.036 x 107

Standard 7.35 mg/l

1.237 x 107

Standard 7.78 mg/l

1.288 x 107

381 Hour Sample A, pH 9

1.068 x 107

381 Hour Sample B, pH 9

9.812 x 106

 


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

Table 9.3 pH 4 at 50.0 ± 0.5ºC

 

Time (Hours)

Initial (A)

Initial (B)

24 (A)

24 (B)

120 (A)

120 (B)

Concentration (g/l)

1.52 x 10-2

1.52 x 10-2

1.46 x 10-2

1.50 x 10-2

1.44 x 10-2

1.44 x 10-2

% of mean initial concentration

100

100

96.2

98.5

94.7

94.9

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

Table 9.4 pH 7 at 50.0 ± 0.5ºC

 

Time (Hours)

Initial (A)

Initial (B)

24 (A)

24 (B)

120 (A)

120 (B)

Concentration (g/l)

1.53 x 10-2

1.53 x 10-2

1.45 x 10-2

1.45 x 10-2

1.32 x 10-2

1.34 x 10-2

Log10[concentration (g/l)]

-1.814

-1.816

-1.839

-1.838

-1.879

-1.873

% of mean initial concentration

100

99.8

94.6

95.0

86.3

87.6

Table 9.4 continued pH 7 at 50.0 ± 0.5ºC

 

Time (Hours)

381 (A)

381 (B)

Concentration (g/l)

1.18 x 10-2

1.21 x 10-2

Log10[concentration (g/l)]

-1.929

-1.916

% of mean initial concentration

77.0

79.3

Result:The data resulted in a pseudo-second order plot, see Figure 9.1 (Attachment 2 of this Summary), for which the quantification of rate constants was beyond the scope of the guideline methodology. To generate data for environmental assessment, a second test, performed directly at 25.0±0.5°C for a period of 32 days, was performed.


Table 9.5 pH 9 at 50.0 ± 0.5ºC

 

Time (Hours)

Initial (A)

Initial (B)

24 (A)

24 (B)

120 (A)

120 (B)

Concentration (g/l)

1.56 x 10-2

1.56 x 10-2

1.48 x 10-2

1.50 x 10-2

1.42 x 10-2

1.40 x 10-2

% of mean initial concentration

100

100

94.7

96.2

91.1

89.6

Table 9.5 continued pH 9 at 50.0 ± 0.5ºC

 

Time (Hours)

216 (A)

216 (A)

381 (B)

381 (B)

Concentration (g/l)

1.36 x 10-2

1.35 x 10-2

1.28 x 10-2

1.18 x 10-2

% of mean initial concentration

87.3

86.7

82.0

75.4

Result:          Less than 10% hydrolysis after 5 days at 50°C (mean hydrolysis 9.6%), equivalent to a half-life greater than 1 year at 25°C.


Additional testing directly at 25°C

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

Table 9.6

Solution

Mean Peak Total Area

Standard 7.46 mg/l

1.289 x 107

Standard 6.36 mg/l

1.064 x 107

Initial Sample A, pH 7, 25ºC

1.251 x 107

Initial Sample B, pH 7, 25ºC

1.272 x 107

Standard 7.58 mg/l

1.319 x 107

Standard 7.23 mg/l

1.255 x 107

74 Hour Sample A, pH 7, 25ºC

1.230 x 107

74 Hour Sample B, pH 7, 25ºC

1.242 x 107

Standard 7.68 mg/l

1.291 x 107

Standard 7.82 mg/l

1.184 x 107

169 Hour Sample A, pH 7, 25ºC

1.232 x 107

169 Hour Sample B, pH 7, 25ºC

1.228 x 107

Standard 7.85 mg/l

1.367 x 107

Standard 8.48 mg/l

1.489 x 107

336 Hour Sample A, pH 7, 25ºC

1.220 x 107

336 Hour Sample B, pH 7, 25ºC

1.222 x 107

Standard 7.62 mg/l

1.188 x 107

Standard 7.46 mg/l

1.298 x 107

504 Hour Sample A, pH 7, 25ºC

1.198 x 107

504 Hour Sample B, pH 7, 25ºC

1.222 x 107

Standard 7.79 mg/l

1.320 x 107

Standard 7.66 mg/l

1.338 x 107

672 Hour Sample A, pH 7, 25ºC

1.191 x 107

672 Hour Sample B, pH 7, 25ºC

1.201 x 107

Standard 8.49 mg/l

1.383 x 107

Standard 8.94 mg/l

1.331 x 107

768 Hour Sample A, pH 7, 25ºC

1.217 x 107

768 Hour Sample B, pH 7, 25ºC

1.218 x 107


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

Table 9.7 pH 7 at 25.0 ± 0.5ºC

 

Time (Hours)

Initial (A)

Initial (B)

74 (A)

74 (B)

169 (A)

169 (B)

Concentration (g/l)

1.47 x 10-2

1.50 x 10-2

1.42 x 10-2

1.43 x 10-2

1.54 x 10-2

1.54 x 10-2

% of mean initial concentration

99.2

101

95.4

96.4

104

104

Table 9.7 continuedpH 7 at 25.0 ± 0.5ºC

 

Time (Hours)

336 (A)

336 (B)

504 (A)

504 (B)

672 (A)

672 (B)

Concentration (g/l)

1.40 x 10-2

1.40 x 10-2

1.45 x 10-2

1.48 x 10-2

1.38 x 10-2

1.40 x 10-2

% of mean initial concentration

94.1

94.2

97.9

99.8

93.2

94.0

Table 9.7 continued pH 7 at 25.0 ± 0.5ºC

 

Time (Hours)

768 (A)

768 (B)

Concentration (g/l)

1.56 x 10-2

1.56 x 10-2

% of mean initial concentration

105

105

 

Result:          No evidence of hydrolysis was observed over the period of 32 days. All analysis resulted in a test item recovery of 100±6% of the initial concentration, demonstrating random experimental variance only without any underlying trend. In addition, the data confirmed a hydrolytic half-life of greater than 1 year at 25°C.


Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
The linearity of the detector response with respect to concentration was assessed over the nominal concentration range of 0 to 10 mg/l. This was satisfactory with a correlation coefficient of 1.000 being obtained for the analysis matrix for all 3 pH’s in
Conclusions:
The estimated half-life at 25°C of the test material 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 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. 

Conclusion

The estimated half-life at 25°C for the test item is shown in the following table:

Table 9.8

pH

Estimated half-life at 25°C

4

>1 year

7

>1 year

9

>1 year