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Hydrolysis

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Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1989-09-18, 1989-10-20
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Qualifier:
according to
Guideline:
other: EEC directive 84/449 C10
Deviations:
yes
Remarks:
The test was performed at pH 4 and pH 7 only. The substance solubility at pH 9 is too low.
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Deviations:
yes
Remarks:
The test was performed onlyat pH 4 and pH 7. At pH 9 the substance solubility is is too low.
GLP compliance:
no
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):


OTHER PROPERTIES (if relevant for this endpoint)
- Solubility in buffer solution at pH 7 : 0.00075 g/L
- Solubility in buffer solution at pH 9 : 0.00003 g/L

The solutions of the test substance are very sensitive to light. Therefore, the solutions were prepared and handled under red light and stored in the darkness
Radiolabelling:
no
Analytical monitoring:
yes
Details on sampling:
- Sampling intervals for the parent/transformation products: At the end of the test
- Sampling method: 2 mL aliquote of the test solution
- Sample storage conditions before analysis: In the dark
Buffers:
- pH: 4
- Type and final molarity of buffer: Standard acetate buffer
- Composition of buffer: (0.1 mole/L acetic acid + 0.1 mole/L sodium acetate ) + 15 mL acetic acid per liter
- pH: 7
- Type and final molarity of buffer: Phosphate buffer
- Composition of buffer: (0.041 mole di-sodium-hydrogenphosphate + 0.028 mole potassium-dihydrogenphosphate) per liter
- pH: 9
- Composition of buffer: (0.043 mole di-sodium-tetraborate + 0.017 mole potassium-dihydrogenphosphate) per liter
Details on test conditions:
TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: Sterlie 100.0 mL amber volumetric flask
- Sterilisation method: Filtration (0.22 µm)
- Measures taken to avoid photolytic effects: Solutions were prepared and handled under red light and stored in the darkness
- Measures to exclude oxygen: By bubbling argon for 5 minutes
- Is there any indication of the test material adsorbing to the walls of the test apparatus? No
Number of replicates:
2
Positive controls:
no
Negative controls:
no
Preliminary study:
The substance was found to be hydrolytically stable in the preliminary tests. See tables below.
Transformation products:
no
% Recovery:
98.6
pH:
4
Temp.:
50 °C
Duration:
5 d
% Recovery:
93.8
pH:
7
Temp.:
50 °C
Duration:
5 d
Remarks on result:
hydrolytically stable based on preliminary test

Table 1. Preliminary test after 2.4 hours at 50 °C.


pH 4 pH 7
run 1st 2nd 1st 2nd
initial conc. Co in g/L 0.00031 0.00031 0.00031 0.00031
final conc. Ct in g/L 0.00031 0.00031 0.00030 0.00030
100x(Co-Ct)/Co in % -0.1 -0.5 1.9 0.9
mean value (%) -0.3 1.4

Negative values of (Co - Ct)/Co are found for several determinations that means that the concentration of the test substance measured at time = t is greater than the concentation at test start: the difference corresponds to the error (precision) of the analysis method.

Table 2. Preliminary test after 5 days at 50 °C.


pH 4 pH 7
run 1st 2nd 1st 2nd
initial conc. Co in g/L 0.00030 0.00030 0.00030 0.00030
final conc. Ct in g/L 0.00031 0.00030 0.00029 0.00029
100x(Co-Ct)/Co in % 0.5 2.3 7.0 5.5
mean value (%) 1.4 6.2
Validity criteria fulfilled:
yes
Conclusions:
The test substance is stable at pH 4 and 7 (less than 10 % decomposition after 5 days).
Executive summary:

In this guideline (equivalent to OECD 111) study, the test material (EC 404-363-3) was determined to be hydrolytically stable at pH 4 and pH 7

Description of key information

 Study conducted to recognised testing guideline.

Key value for chemical safety assessment

Additional information

A study on hydrolysis as a fuction of pH was conducted according to EEC directive 84/449 C.10 (CIBA-GEIGY Ltd. 1989). The test substance is stable at pH 4 and pH 7 (less than 10 % decomposition after 5 days at 50 °C) . However, the hydrolysis test could not be performed at pH 9 because the solubility of the test substance in the buffer solution at pH 9 is too low.

In contact with water the substance will hydrolyse slowly.