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Administrative data

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
The study was conducted between 24 October 2007 and 14 November 2007.
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2007
Report date:
2007

Materials and methods

Test guideline
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)

Test material

Constituent 1
Reference substance name:
Magenta T-43
IUPAC Name:
Magenta T-43
Test material form:
solid: particulate/powder
Details on test material:
Sponsor's identification: MAGENTA T-43
Description: dark red solid
Storage conditions: room temperature, in the dark
Lot number: H186-5
Radiolabelling:
no

Study design

Analytical monitoring:
yes
Details on sampling:
Analysis of sample solutions:
Aliquots of the sample solutions were taken from the flasks 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:
Duplicate samples (A and B) were analysed neat.


Buffers:
The specification of buffered solutions were as follows:

Potassium hydrogen phthalate; pH 4; conc. 0.005 mol dm-3
Disodium hydrogen orthophophate (anhydrous); pH 7; conc. 0.003 mol dm-3
Potassium dihydrogen orthophosphate; pH 7; conc. 0.002 mol dm-3
Sodium chloride; pH 7; conc. 0.002 mol dm-3
Disodium tetraborate; pH 9; conc. 0.001 mol dm-3
Sodium chloride; pH 9; conc. 0.002 mol dm-3


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):
Not applicable
Details on test conditions:
Preparation of samples:
Sample solutions were prepared in stoppered glass flasks at a nominal concentration of 0.2 g/l in the three buffer solutions.

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 5 days.
Duration of testopen allclose all
Duration:
120 h
pH:
4
Temp.:
50
Duration:
120 h
pH:
7
Temp.:
50
Duration:
120 h
pH:
9
Temp.:
50
Number of replicates:
Samples:
Duplicate samples (A and B)

Standards:
Duplicate standard solutions
Positive controls:
no
Negative controls:
no

Results and discussion

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
Details on results:
Results:
For pH 4, 7 and 9 the results show that less than 10% hydrolysis was achieved 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

Validation:

The linearity of the detector response with respect to concentration was assessed over the nominal concentration range of 0 to 500 mg/l. This was satisfactory with a correlation coefficient of 1.00 being obtained.

Preliminary Test Results

Solution

Mean Peak Area

Standard 202 mg/l

Standard 200 mg/l

Initial Sample A, pH4

Initial Sample B, pH 4

2032

2001

2049

2068

Standard 202 mg/l

Standard 200 mg/l

Initial Sample A, pH 7

Initial Sample B, pH 7

2036

2014

2064

2058

Standard 202 mg/l

Standard 200 mg/l

Initial Sample A, pH 9

Initial Sample B, pH 9

2027

2017

2037

2037

Standard 201 mg/l

Standard 203 mg/l

24 Hour Sample A, pH 4

24 Hour Sample B, pH 4

1656

1679

1693

1703

Standard 201 mg/l

Standard 203 mg/l

24 Hour Sample A, pH 7

24 Hour Sample B, pH 7

1664

1680

1702

1716

Standard 201 mg/l

Standard 203 mg/l

24 Hour Sample A, pH 9

24 Hour Sample B, pH 9

1659

1689

1691

1688

Standard 202 mg/l

Standard 202 mg/l

48 Hour Sample A, pH 4

48 Hour Sample B, pH 4

1692

1694

1709

1695

Standard 202 mg/l

Standard 202 mg/l

48 Hour Sample A, pH 7

48 Hour Sample B, pH 7

1700

1685

1706

1689

Standard 202 mg/l

Standard 202 mg/l

48 Hour Sample A, pH 9

48 Hour Sample B, pH 9

1699

1685

1686

1686

Standard 202 mg/l

Standard 202 mg/l

120 Hour Sample A, pH 4

120 Hour Sample B, pH 4

1669

1679

1711

1707

Standard 202 mg/l

Standard 202 mg/l

120 Hour Sample A, pH 7

120 Hour Sample B, pH 7

1684

1692

1718

1721

Standard 202 mg/l

Standard 202 mg/l

120 Hour Sample A, pH 9

120 Hour Sample B, pH 9

1670

1691

1686

1682

 

Main Test Results:

pH 4 at 50.0 ± 0.5°C

 

Time (Hours)

 

0

24

48

120

Concentration (g/l)

0.206

0.206

0.203

0.206

% of initial

100

100

98.9

100

 

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°C

 

Time (Hours)

 

0

24

48

120

Concentration (g/l)

0.205

0.206

0.203

0.206

% of initial

100

100

98.9

100

 

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°C

 

                                 Time (Hours)

 

0

24

48

120

Concentration (g/l)

0.203

0.204

0.201

0.202

% of initial

100

100

99.3

99.6

 

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

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The estimated half-life at 25 °C of the test material at pH 4, pH 7 and pH 9 has been shown to be >1 year.
Executive summary:

The estimated half-life of the test substance Magenta T-43 was shown to be >1 year at pH 4, 7 and 9 at 25 °C according to method C7 of Commission Directive 92/69/EEC using the Hydrolysis as a Function of pH test method.