Registration Dossier

Administrative data

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1990

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Details on test material:
orange-red
Specific details on test material used for the study:
Chemical Name: 1-(2'-Hydroxyethyl)-amino-4-methyl-2-nitro-benzene
Batch Data: B 3/89
Purity: 98%
Molecular Mass: 196 g/mole
Formula: C9H12N2O3
Radiolabelling:
no

Study design

Details on sampling:
The test article was dissolved in the buffer solutions specified above. For this purpose a stock solution containing 10 mg of the test article per 100 ml water was diluted with buffer solution to yield a test article concentration of 10 mg/l.
Buffers:
Buffer solutions were prepared as follows, according to OECD guideline 111:
Citrate buffer pH 4.0 according to Kalthoff & Vleeschhouwer:
100 ml of 0.1-M-potassium dihydrogencitrate solution and 18 ml of 0.1-N-NaOH were diluted to 200 ml with water. The pH of this solution was adjusted to 4.0 with additional 0.1-N-NaOH.
Phosphate buffer pH 7.0 according to Clark & Lubs:
100 ml of 0.1-M-potassium dihydrogenphosphate solution and 59.3 ml of 0.1-N-sodium hydroxide solution were diluted to 200 ml with water. The pH of this solutionwas adjusted to 7.0 with additional 0.1-N-NaOH.
Borate buffer pH 9.0 according to Clark & Lubs:
3 g of boric acid and 3. 7 g of potassium chloride were dissolved in 500 ml of water to yield a concentration of 0.1 mol/l for each compound. 100 ml of this solutionplus 42.6 ml of 0.1-N-sodium hydroxide solution were diluted with water ad 200 ml. The pH of this solution was adjusted to 9.0 with additional 0.1-N-NaOH.
In all cases, water was degassed by bubbling nitrogen through the liquid for about 20 min immediately before use.

Results and discussion

Preliminary study:
Initially, an orientating preliminary test at 50 °C and pH values of 4.0, 7.0 and 9.0 was performed as specified by OECD guideline 111.
Test performance:
The test article was found to exhibit no degradation in excess of 10 % during the preliminary test. Therefore, in accordance witb OECD guideline 111, no main testwas performed.
Transformation products:
no
Total recovery of test substance (in %)open allclose all
% Recovery:
>= 100 - <= 100
pH:
4
Temp.:
50 °C
Duration:
>= 1 - <= 5 d
Remarks on result:
hydrolytically stable based on preliminary test
% Recovery:
>= 100 - <= 100
pH:
7
Temp.:
50 °C
Duration:
>= 1 - <= 5 d
Remarks on result:
hydrolytically stable based on preliminary test
% Recovery:
>= 99 - <= 100
pH:
9
Temp.:
50 °C
Duration:
>= 1 - <= 5 d
Remarks on result:
hydrolytically stable based on preliminary test
Dissipation half-life of parent compoundopen allclose all
Key result
pH:
4
Temp.:
50 °C
Remarks on result:
hydrolytically stable based on preliminary test
Key result
pH:
7
Temp.:
50 °C
Remarks on result:
hydrolytically stable based on preliminary test
Key result
pH:
9
Temp.:
50 °C
Remarks on result:
hydrolytically stable based on preliminary test
Details on results:
The test article stock solution was diluted with the individual buffers (pH 4, 7 and 9) as indicated above and the solutions were filtered through 0.22 µL disposable filter units. Duplicate samples of each buffered solution were prepared and transferred to 50 ml glass flasks. A sample each was taken to determine the initial concentration of the test article. The flasks were sealed with aluminium crimp caps and silicone ruhher septa and incubated in a water bath at 50 °C. Care was taken to include only small volumes of air in these vessels. Samples were taken after 1, 3 and 4 days and analysed by HPLC as described. Since in this period no degradation was observed, the test was finished after this interval. For a duplicate performance of this test, sample concentrations were determined initially and after 4 days.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The test article was subjected to a preliminary test for hydrolytic stability, applying a temperature of 50 °C at pH 4.0, 7.0 and 9.0. Under these conditions, no continuous decrease in concentration was observed. Methylgelb can therefore be considered hydrolytically stable according to OECD guideline 111.