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Diss Factsheets

Administrative data

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
The study was conducted between 10 June 2005 and 11 August 2005
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2005
Report date:
2005

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
Diammonium phthalate
EC Number:
208-341-9
EC Name:
Diammonium phthalate
Cas Number:
523-24-0
Molecular formula:
C8H6O4.2H3N
IUPAC Name:
diammonium phthalate
Test material form:
solid: crystalline
Specific details on test material used for the study:
Description: white crystalline solid
Lot number: 4172005
Date recieved: 02 June 2005
Storage conditions: room temperature, in the dark
Radiolabelling:
no

Study design

Analytical monitoring:
yes
Details on sampling:
The sample solution vessels were taken from the water bath at various times and the pH of each sample recorded.
The concentration of the sample solution was determined by high performance liquid chromatography (HPLC).



Buffers:
- pH: 4
- Composition of buffer:
Potassium hydrogen citrate: 1.00 x 10^-2 mol dm^-3
Sodium hydroxide: 1.80 x 10^-3 mol dm^-3

- pH: 7
- Composition of buffer:
Disodium hydrogen orthophosphate (anhydrous): 6.00 x 10^3 mol dm^-3
Potassium dihydrogen orthophosphate: 4.00 x 10^·3 mol dm^-3
Sodium chloride: 4.00 x 10^-3 mol dm^-3

- pH: 9
- Composition of buffer:
Disodium tetraborate: 2.00 x 10^-3 mol dm^-3
Sodium chloride: 4.00 x 10^-3 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.
Details on test conditions:
Preparation of samples
Sample solutions were prepared in stoppered glass flasks at a nominal concentration of 2.0 g/l in the three buffer solutions. 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
Sample solutions at pH 4, 7 and 9 were maintained at 50.0 ± 0.5°C for a period of 5 days.


The phthalate component and the ammonium compnent were analysed separately

Duration of testopen allclose all
Duration:
120 h
pH:
4
Temp.:
50 °C
Initial conc. measured:
2 g/L
Duration:
120 h
pH:
7
Temp.:
50 °C
Initial conc. measured:
2 g/L
Duration:
120 h
pH:
9
Temp.:
50 °C
Initial conc. measured:
2 g/L
Number of replicates:
Duplicate aliquots of sample solution were analysed
Positive controls:
no
Negative controls:
no

Results and discussion

Preliminary study:
Phthalate component:
pH4: Less than 10% hydrolysis after 5 days at 50°C, equivalent to a half-life greater than 1 year at 25°C.
pH7: Less than 10% hydrolysis after 5 days at 50°C, equivalent to a half-life greater than 1 year at 25°C.
pH9: Less than 10% hydrolysis after 5 days at 50°C, equivalent to a half-life greater than 1 year at 25°C.

Ammonium component:
pH4: Less than 10% hydrolysis after 5 days at 50°C, equivalent to a half-life greater than 1 year at 25°C.
pH7: Less than 10% hydrolysis after 5 days at 50°C, equivalent to a half-life greater than 1 year at 25°C.
pH9: Less than 10% hydrolysis after 5 days at 50°C, equivalent to a half-life greater than 1 year at 25°C.
Transformation products:
not measured
Total recovery of test substance (in %)open allclose all
% Recovery:
>= 98.5 - <= 99
pH:
4
Temp.:
50 °C
Duration:
120 h
Remarks on result:
other: phthalate component
% Recovery:
>= 98.6 - <= 99.8
pH:
7
Temp.:
50 °C
Duration:
120 h
Remarks on result:
other: phthalate component
% Recovery:
>= 99.2 - <= 101
pH:
9
Temp.:
50 °C
Duration:
120 h
Remarks on result:
other: phthalate component
% Recovery:
>= 96.8 - <= 99.7
pH:
4
Temp.:
50 °C
Duration:
120 h
Remarks on result:
other: ammonium component
% Recovery:
>= 97.1 - <= 97.5
pH:
7
Temp.:
50 °C
Duration:
120 h
Remarks on result:
other: ammonium component
% Recovery:
>= 99 - <= 101
pH:
9
Temp.:
50 °C
Duration:
120 h
Remarks on result:
other: ammonium component
Dissipation DT50 of parent compoundopen allclose all
pH:
4
Temp.:
25 °C
DT50:
> 1 yr
Remarks on result:
hydrolytically stable based on preliminary test
pH:
7
Temp.:
25 °C
DT50:
> 1 yr
Remarks on result:
hydrolytically stable based on preliminary test
pH:
9
Temp.:
25 °C
DT50:
> 1 yr
Remarks on result:
hydrolytically stable based on preliminary test

Any other information on results incl. tables

 The phthalate component concentrations at the given time points are shown in the following tables:

pH 4 at 50.0 ± 0.5°C

 

Time (Hours)

0 A

0 B

120 A

120 B

Concentration (g/l)

1.98

1.98

1.95

1.96

% of initial

-

-

98.5

99.0

 

pH 7 at 50.0 ± 0.5°C

 

Time (Hours)

0 A

0 B

120 A

120 B

Concentration (g/l)

2.00

1.98

1.99

1.96

% of initial

-

-

99.8

98.6

 

pH 9 at 50.0 ± 0.5°C

 

Time (Hours)

0 A

0 B

120 A

120 B

Concentration (g/l)

1.99

1.98

1.97

1.99

% of initial

-

-

99.2

101

 

The ammonium component concentrations at the given time points are shown in the following tables:

 

pH 4 at 50.0 ± 0.5°C

 

Time (Hours)

0 A

0 B

120 A

120 B

Concentration (g/l)

1.95

2.02

1.94

1.95

% of initial

-

-

99.7

96.8

 

pH 7 at 50.0 ± 0.5°C

 

Time (Hours)

0 A

0 B

120 A

120 B

Concentration (g/l)

2.00

2.00

1.94

1.95

% of initial

-

-

97.1

97.5

 

pH 9 at 50.0 ± 0.5°C

 

Time (Hours)

0 A

0 B

120 A

120 B

Concentration (g/l)

1.98

1.97

1.96

1.99

% of initial

-

-

99.0

101

 

Validation

Linearities of the detector response with respect to concentration were assessed over the nominal concentration range of 0 to 200 mg/I. The results are as follows:

Component

pH

Correlation Coefficient

phthalate

4

1.000

phthalate

7

1.000

phthalate

9

1.000

ammonium

4

1.000

ammonium

7

1.000

ammonium

9

1.000

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The estimated half-lives at 25°C of the test material are as follows:

Component pH Estimated Half-life at 25°C
phthalate 4 > 1 year
phthalate 7 > 1 year
phthalate 9 > 1 year
ammonium 4 > 1 year
ammonium 7 > 1 year
ammonium 9 > 1 year
Executive summary:

Assessment of hydrolytic stability was carried out using Method 111 of the OECD Guidelines for Testing of Chemicals, 13 April 2004. The results are as follows:

Component              pH                                 Estimated Half-life at 25°C

phthalate                    4                                              > 1 year

phthalate                    7                                              > 1 year

phthalate                    9                                              > 1 year

ammonium                  4                                              > 1 year

ammonium                  7                                              > 1 year

ammonium                  9                                              > 1 year