Registration Dossier

Environmental fate & pathways

Hydrolysis

Currently viewing:

Administrative data

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Experimental Starting Date: 20 July 2012; Experimental Completion Date: 23 January 2013
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 not effect the quality of the relevant results.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2013

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
Deviations:
no
Qualifier:
according to guideline
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EPA OPPTS 835.2120 (Hydrolysis of Parent and Degradates as a Function of pH at 25°C)
Deviations:
no
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Test material form:
other: solid
Radiolabelling:
no

Study design

Analytical monitoring:
yes
Details on sampling:
Preparation of the Test Solutions:
Sample solutions were prepared in stoppered glass flasks at a nominal concentration of 0.500 g/L in the three buffer solutions.

The concentration of each solution did not exceed the lesser of 0.01 mol/L or half the water 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.

Tier 2:

Results from the preliminary test/tier 1 showed it was necessary to undertake further testing at pH 9. Sample solutions were maintained at 50.0 ± 0.5, 60.0 ± 0.5 °C and 70.0 ± 0.5 °C for periods of 239 hours, 141¼ hours and 48 hours respectively.

Analysis of sample solutions:
Duplicate vessels of sample solutions for each pH were taken from the waterbath 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:
An aliquot of each pH 4 and pH 7 sample solution was diluted by a factor of 10 using dimethyl sulfoxide.

An aliquot of each pH 9 sample solution was diluted by a factor of 10 using acidified dimethyl sulfoxide.

Standards:
For pH 4 and pH 7 sample solution analysis, duplicate standard solutions of test item were prepared in dimethyl sulfoxide: relevant buffer solution (90:10 v/v) at a nominal concentration of 50 mg/L.
For pH 9 sample solution analysis, duplicate standard solutions of test item were prepared in acidified dimethyl sulfoxide : pH 9 buffer solution (90:10 v/v) at a nominal concentration of 50 mg/L.

Matrix blanks:
For pH 4 and pH 7 sample solution analysis, dimethyl sulfoxide: relevant buffer solution (90:10 v/v).

For pH 9 sample solution analysis, acidified dimethyl sulfoxide: pH 9 buffer solution (90:10 v/v).


















Buffers:
The test system uses sterile buffer solutions at pH's 4.0, 7.0 and 9.0

Specification of buffer solutions:
Buffer Solution (pH 4)
Components: Citric acid, Sodium chloride, Sodium hydroxide
Concentration (mol dm-3): 0.06, 0.04, 0.07

Buffer Solution (pH7)
Components: Disodium hydrogen orthophosphate (anhydrous), Potassium dihydrogen orthophosphate, Sodium chloride
Concentration (mol dm-3): 0.03, 0.02, 0.02

Buffer Solution (pH9)
Components: Disodium tetraborate, Sodium chloride
Concentration (mol dm-3): 0.01, 0.02
Details on test conditions:
Refer to details on sampling and analytical methods.
Duration of testopen allclose all
Duration:
120 h
Temp.:
50 °C
Initial conc. measured:
0.478 - 0.504 g/L
Duration:
239 h
pH:
9
Temp.:
50 °C
Initial conc. measured:
0.534 g/L
Duration:
141.25 h
pH:
9
Temp.:
60 °C
Initial conc. measured:
0.534 g/L
Duration:
48 h
pH:
9
Temp.:
70 °C
Initial conc. measured:
0.516 g/L
Number of replicates:
Duplicate
Positive controls:
no
Negative controls:
no

Results and discussion

Preliminary study:
See any other information on results incl. tables.
Test performance:
Validation:
The linearity of the detector response with respect to concentration was assessed over the nominal concentration range of 0 to 100 mg/L. This was satisfactory with a correlation coefficient of 1.000 being obtained for the analysis matrices relevant to all three pHs.
Transformation products:
not measured
Dissipation DT50 of parent compoundopen allclose all
pH:
4
Temp.:
25 °C
DT50:
> 1 yr
Type:
(pseudo-)first order (= half-life)
pH:
7
Temp.:
25 °C
DT50:
> 1 yr
Type:
(pseudo-)first order (= half-life)
pH:
9
Temp.:
25 °C
DT50:
82.7 d
Type:
(pseudo-)first order (= half-life)
Details on results:
See any other information on results incl. tables.

Any other information on results incl. tables

Results

Preliminary test/Tier 1

The mean peak areas relating to the standard and sample solutions are shown in attached background material.

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

pH 4 at 50.0 ± 0.5 ºC 

Timepoint (hours)

Sample Replicate

Concentration (g/L)

% of Mean Initial Concentration

Initial

A

0.504

100

B

0.504

100

24

A

0.515

102

B

0.516

102

120

A

0.510

101

B

0.508

101

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

pH 7 at 50.0 ± 0.5 ºC 

Timepoint (hours)

Sample Replicate

Concentration (g/L)

% of Mean Initial Concentration

Initial

A

0.495

99.8

B

0.497

100

24

A

0.500

101

B

0.500

101

120

A

0.471

95.1

B

0.471

95.0

 Result:             Less than 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 ± 0.5 ºC

Timepoint (hours)

Sample Replicate

Concentration (g/L)

% of Mean Initial Concentration

Initial

A

0.478

99.6

B

0.481

100

24

A

0.416

86.7

B

0.412

85.9

120

A

0.242

50.6

B

0.242

50.4

 Result:             The extent of hydrolysis after 120 hours indicated that a further test (Tier 2), conducted at 50.0, 60.0 and 70.0°C, was required to estimate the rate constant and half-life.

Tier 2

The mean peak area relating to the standard and sample solutions are shown in attached background material.

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

 

pH 9 at 50.0 ± 0.5 ºC

 

Timepoint (hours)

Sample Replicate

Concentration (g/L)

Log10[concentration (g/L)]

% of Mean Initial Concentration

Initial

A

0.534

-0.272

99.9

B

0.535

-0.272

100

51¼

A

0.386

-0.414

72.1

B

0.387

-0.412

72.4

72

A

0.341

-0.467

63.8

B

0.339

-0.470

63.4

118

A

0.257

-0.589

48.1

B

0.261

-0.583

48.8

168

A

0.196

-0.709

36.6

B

0.195

-0.710

36.4

239

A

0.132

-0.880

24.7

B

0.131

-0.882

24.6

 

Result: Slope     =         -2.54 x 10-4 (see Figure 3.4 - Graph of log10 Concentration (g/L) versus Time (Hours) - attached background material).
kobs
                  =         5.84 x 10-3 hour-1
                       =         1.62 x 10-6 second-1
t½
                   =         119 hours

 

pH 9 at 60.0 ± 0.5 ºC

 

Timepoint (hours)

Sample Replicate

Concentration (g/L)

Log10[concentration (g/L)]

% of Mean Initial Concentration

Initial

A

0.534

-0.272

99.9

B

0.535

-0.272

100

24

A

0.354

-0.451

66.3

B

0.354

-0.451

66.2

48

A

0.241

-0.618

45.1

B

0.240

-0.620

44.9

72

A

0.175

-0.758

32.7

B

0.167

-0.776

31.3

96

A

0.116

-0.934

21.8

B

0.116

-0.934

21.8

118

A

8.10 x 10-2

-1.091

15.2

B

8.03 x 10-2

-1.095

15.0

141¼

A

5.40 x 10-2

-1.268

10.1

B

5.32 x 10-2

-1.274

9.96

 

Result: Slope      =         -6.97 x 10-3 (see Figure 3.5 - Graph of log10 Concentration (g/L) versus Time (Hours) - attached background material).
kobs
                  =         1.60 x 10-2 hour-1
                       =         4.46 x 10-6 second-1
t½
                   =         43.2 hours

pH 9 at 70.0 ± 0.5 ºC

 

Timepoint (hours)

Sample Replicate

Concentration (g/L)

Log10[concentration (g/L)]

% of Mean Initial Concentration

Initial

A

0.516

-0.287

99.9

B

0.517

-0.286

100

3

A

0.461

-0.336

89.2

B

0.460

-0.337

89.1

A

0.408

-0.389

79.0

B

0.413

-0.384

80.0

22½

A

0.202

-0.695

39.1

B

0.202

-0.694

39.2

25½

A

0.179

-0.747

34.6

B

0.180

-0.745

34.8

28½

A

0.159

-0.799

30.8

B

0.160

-0.797

30.9

48

A

7.12 x 10-2

-1.148

13.8

B

7.10 x 10-2

-1.149

13.8

 

Result: Slope      =         -1.80 x 10-2 (see Figure 3.6 - Graph of log10 Concentration (g/L) versus Time (Hours) - attached background material).
kobs
                  =         4.14 x 10-2hour-1
                       =         1.15 x 10-5 second-1
t½
                   =         16.7 hours

The Arrhenius plot was constructed using the data shown in the following table:

 

pH 9 Arrhenius Data

 

T (ºC)

T (K)

1 / T (K)

kobs (hr-1)

Ln kobs

50.0

323.15

3.10 x 10-3

5.84 x 10-3

-5.143

60.0

333.15

3.00 x 10-3

1.60 x 10-2

-4.133

70.0

343.15

2.91 x 10-3

4.14 x 10-2

-3.184

 

From the graph (Figure 3.7 - Graph of In.kobs versus 1/T (K), attached background material) of the above data, the rate constant and half-life at 25°C have been estimated to be as follows:

 

kobs    =         3.49 x 10-4 hour-1
           =         9.71 x 10-8 second-1
t½       =         1.98 x 103 hours
           =         82.7 days


 



Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The hydrolysis characteristics of the test item have been quantified for the substituted-(naphthalen-1-methyl)heteromonocyclic chloride content of the test item. The rate constant and estimated half-life at 25 °C of the test item are summarised below:

The rate constant and estimated half-life at 25 °C of the test item are:
pH 4: Rate constant (s-1): not applicable
Estimated half-life at 25°C: >1 year

pH 7: Rate constant (s-1): not applicable
Estimated half-life at 25°C: >1 year

pH 9: Rate constant (s-1): 9.71 x 10-8
Estimated half-life at 25°C: 82.7 days

No hydrolysis testing was relevant to the propane-1,2-diol content of the test item, as it did not contain any hydrolysable functional groups and also from available information, it was expected to be readily biodegradable.
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, Method 111 of the OECD Guidelines for Testing of Chemicals, 13 April 2004, and Method 835.2120 of the OPPTS Guidelines.

 

The test system uses sterile buffer solutions at pH’s 4.0, 7.0 and 9.0.

 

Results

The hydrolysis characteristics of the test item have been quantified for the substituted-(naphthalen-1-methyl)heteromonocyclic chloride content of the test item. The rate constant and estimated half-life at 25°C of the test item are shown in the following table:

 

pH

Rate constant (s-1)

Estimated half-life at 25°C

4

not applicable

>1 year

7

not applicable

>1 year

9

9.71 x 10-8

82.7 days

 

 

No hydrolysis testing was relevant to the propane-1,2-diol content of the test item, as it did not contain any hydrolysable functional groups and also from available information, it was expected to be readily biodegradable.