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Hydrolysis

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Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2004
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
The test substance of the HPLC test sample obtained from a pre-treatment was analyzed using high performance liquid chromatography based on the following conditions. The concentration of the test substance in the HPLC sample was compared to the peak area obtained from standard solutions and HPLC sample chromatograms, and comparative calculations were made.
The lower limit for the peak area took noise into consideration, and was set to 1100uV-sec (test substance concentration of 0.0940mg/L)

Conditions
Equipment High performance liquid chromatograph Manufactured by Shimadzu LC-2010A
Column L-column ODS (manufactured by Chemicals Evaluation and Research Institute) 15cm x 2.1mm I.D.
Column Temperature 40°C
Eluent Methanol / phosphoric acid buffer* (45/55 V/V)
Flow Rate 0.2 mL/min
Measured Wavelength 225nm
Injection Amount 2uL
Inspector Output 1V/AU
* 5mmol/L potassium dihydrogen phosphoric acid containing 5mmol/L sodium pentanesulfonate adjusted to a pH of 3.0 using phosphoric acid (1+10)

Preparation of the Standard Solution
The standard solution was prepared as follows in order to determine the concentration of the test substance in the sample for analysis.
100mg of the test substance was used for 1000mg/L of the test substance dissolved in methanol. This was diluted with methanol/phosphate buffer solution (1/1 V/V) to get 2.00mg/L of the standard solution.

Creation of the Calibration Curve
1.00, 2.00 and 4.00mg/L of the standard solution were prepared in the same manner as the standard solution. These were analyzed according to the conditions indicated and calibration curves were created from the peak areas and concentrations on the chromatograms.

Calculation of the Residual Test Substance Rate
The residual test substance rate in the test solution was calculated based on the following formula.
Residual Rate (%) = C/Ci x 100
Ci: Initial concentration of the test substance in the test solution (mg/L)
C: Concentration of the test substance in the test solution after 5 days (mg/L)
Buffers:
Preparation of the Buffer Solution
pH 4.0 2.0 mL of 0.1mol/L sodium hydrate and 250 mL of 0.1mol/L potassium hydrogenphthalate were combined with purified water to 500 mL.
pH 7.0 148.15 mL of 0.1mol/L sodium hydrate and 250 mL of 0.1mol/L potassium dihydrogen phosphoric acid were combined with purified water to 500 mL.
pH 9.0 106.5 mL of 0.1mol/L sodium hydrate and 250 mL of 0.1mol/L potassium chloride – 0.1 mol/L boric acid were combined with purified water to 500 mL.

Each buffer solution was aerated for about 5 minutes with nitrogen gas, and filtered and sterilized with a membrane filter (0.22um).
Details on test conditions:
Preparation of the Test Substance Solution
100mg of the test substance was measured with an electronic analytical scale for precision and dissolved in methanol to prepare 1000mg/L of the test substance solution.

Preparation of the Test Solution
1mL of the test substance solution prepared in 2.2 was collected (1mg of the test substance), and 100mL of the buffer solution prepared in 2.1 were each measured as the test solutions. The initial concentration of the test solution was measured.
The tools used in filtering and sterilizing were washed and sterilized with ethanol.

Test Conditions
Test Concentration about 10mg/L
Amount of Test Solution 10mL
pH of Test Solution pH4.0, pH 7.0 and pH 9.0
Test Temperature 50±0.1°C
Test Time 5 days
Measurement Points Two points – at the start and after 5 days (for each pH)
Light Conditions Shaded
Test Container 10mL glass test tube with stopper (covered with aluminum foil)
Number of replicates:
2 (for each measurement point, with one being the start)
Transformation products:
no
% Recovery:
99.7
pH:
4
Temp.:
50 °C
Duration:
5 d
% Recovery:
99.1
pH:
7
Temp.:
50 °C
Duration:
5 d
% Recovery:
99.8
pH:
9
Temp.:
50 °C
Duration:
5 d
Key result
pH:
4
Temp.:
25 °C
DT50:
> 1 yr
Key result
pH:
7
Temp.:
25 °C
DT50:
> 1 yr
Key result
pH:
9
Temp.:
25 °C
DT50:
> 1 yr
Details on results:
Quality criteria:
* Recovery:
Recoveries should range from 90 % to 110 % for labeled and non-labelled chemicals. In case it is technically difficult to reach this range, a recovery of 70 % for non-labelled chemicals is acceptable, but justification should be given. In the present study, recoveries range between ( ) and ( ) %.
* Repeatability and sensitivity of analytical method:
Repeatability of the analytical method used to quantify the test substance and hydrolysis products at later times can be checked by duplicate analysis of the same buffer solutions.
The analytical method should be sufficiently sensitive to quantify test substance concentrations down to 10 % or less of the initial concentration. If relevant, analytical methods should also be sufficiently sensitive to quantify any hydrolysis product representing 10 % or more of applied (at any time of the study) down to 25 % or less of its peak concentration.
* Confidence intervals for hydrolysis kinetic data
Confidence intervals should be computed and presented for all regression coefficients, rate constants, half-lives, and any other kinetic parameters (e.g. DT50).

Validity criteria fulfilled:
yes
Conclusions:
The results from the primary hydrolysis tests have demonstrated that the substance is hydrolytically stable at pH 4, pH 7, and pH 9, at 50°C.
Executive summary:

The hydrolysis of 1,3 Di-o-Tolylguanidine was evaluated in a study performed in accordance with OECD testing guideline 111 and GLP requirements.


The results from the primary hydrolysis tests have demonstrated that the substance is hydrolytically stable at pH 4, pH 7, and pH 9, at 50°C.


No additional testing was required.


Quality criteria were fulfilled.

Description of key information

The substance is hydrolytically stable at pH 4, pH 7, and pH 9, at 50°C
Study performed in accordance with:
- OECD testing guideline 111 and
- GLP requirements.

Key value for chemical safety assessment

Additional information

The hydrolysis of 1,3 Di-o-Tolylguanidine was evaluated in a study performed in accordance with OECD testing guideline 111 and GLP requirements.


The results from the primary hydrolysis tests have demonstrated that the substance is hydrolytically stable at pH 4, pH 7, and pH 9, at 50°C.


No additional testing was required.


Quality criteria were fulfilled.