Registration Dossier

Administrative data

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
10th August 2006 - 29th August 2006
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
other: Body responsible for the test
Title:
Unnamed
Year:
2006
Report date:
2006

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
GLP compliance:
yes

Test material

Constituent 1
Test material form:
solid: particulate/powder
Details on test material:
Light pink tinted powder
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: supplied by Syngenta, CTL, Alderley Park, Macclesfield, Cheshire, Sk10 2TJ, on behalf of AstraZeneca
- Expiration date of the lot/batch: not specified
- Purity test date: 8th May 2006

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: ambient tempareture in the container in which it was received
- Stability under test conditions: not specified
- Solubility and stability of the test substance in the solvent/vehicle: not specified
- Reactivity of the test substance with the solvent/vehicle of the cell culture medium: not specified

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: UL125 test solutions were made up to a nomal 10 mg l^-1 using a solvent stock.
- Preliminary purification step (if any): n/a
- Final dilution of a dissolved solid, stock liquid or gel: A bulk test solution was prepared by the addition of 2.5ml of the solvent stock to 250ml of pH4 buffer solution in a volumetric flask.
- Final preparation of a solid: n/a

FORM AS APPLIED IN THE TEST (if different from that of starting material) : Solution
Radiolabelling:
no

Study design

Analytical monitoring:
yes
Details on sampling:
- Sampling intervals for the parent/transformation products:
- Sampling method: not specified
- Sampling methods for the volatile compounds, if any: n/a
- Sampling intervals/times for pH measurements: Test 1 - 0, 24, 48, 64, 72, 88, 112 and 144 hours. Test 2@60 degrees - 0, 22, 30 and 46 hours. Test 2@70 degress: 0, 22, 30 and 46 hours
- Sampling intervals/times for sterility check:
- Sample storage conditions before analysis: not specified
- Other observation, if any (e.g.: precipitation, color change etc.): not specified
Buffers:
pH 4

164 ml of 0.2M glacial acetic acid solution and 36 ml of 0.2M sodium acetate solution made up to 1000 ml with deionised water
Estimation method (if used):
Test 2 utilises estimatation method of rate constant at 60 and 70 degrees centigrade at pH4.

Where k(obs) = (2.303/t)*log(C0/Ct)

t=time
C0=concentration of the substance at time 0
Ct=concentration of the substance at time t
2.303=conversion factor between natural and base 10 logarithims

concentrations are expressed as grams per litre of moles per litre and the dimension of the constant k(obs) is time^-1

The half life period is defined as the time required to reduce the concentration of the test substance by 50%. To calculate half life the following equation is used:

t(1/2)=0.693/k(obs)

Rate constants (k) for most chemical reactions closely follow the Arrhenius equation:

k=Ae^(-Ea/RT)

where
Ea=activation energy
R=gas constant
T=absolute tempareture
A=constant(the pre-exponential or frequency factor)

This equation expressed the dependence of the rate constant on temperature. It can be used to estimate a rate constant at a certain temperature when it is not practical to do so experimentally by taking the nature logs of both sides:

ln k = ln A - (Ea/RT)

by plotting ln k versus 1/T for the test values, the plot can be extrapolated to give the rate of hydrolysis at a given temperature using the equation of the line obtained by linear regression.
Details on test conditions:
TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: 50 ml conical flasks were covered in foil and stoppered then placed into a shaker waterbath set previously to the required temperature.
- Sterilisation method:
- Lighting: Carried out in a laboratory with reduced lighting (red light)
- Measures taken to avoid photolytic effects: conical flasks covered in foil and carried out in reduced lighting laboratory
- Measures to exclude oxygen: Flasks were stoppered
- Details on test procedure for unstable compounds: Solutions were sampled and analysed with HPLC
- Details of traps for volatile, if any: none
- If no traps were used, is the test system closed/open: Closed
- Is there any indication of the test material adsorbing to the walls of the test apparatus? No
TEST MEDIUM
- Volume used/treatment: 50ml
- Kind and purity of water: n/a
- Preparation of test medium: Concentrations of UL125 were made up to a nominal 10 mg l^-1. This was prepared by addition of 100mg og UL125 to a 100ml volumetric flask made up to volume with acetonitrile. A bulk test solution was prepared by the addition of 2.5ml of a solvent stock to 250ml of a pH 4 buffer solution in a columetric flask. the pH of the bulk solution was recorded using an indicator stick. Test vessels were then prepared in triplicate by decanting approximately 50ml of the bulk solution into a 50ml conical flask.
- Renewal of test solution: n/a
- Identity and concentration of co-solvent: n/a
OTHER TEST CONDITIONS
- Adjustment of pH: not required. pH of the buffer solution did not alter over the period of the test.
- Dissolved oxygen: n/a
Duration of testopen allclose all
Duration:
144 h
pH:
4
Temp.:
50 °C
Initial conc. measured:
ca. 10 mg/L
Duration:
72 h
pH:
4
Temp.:
60 °C
Initial conc. measured:
ca. 10 mg/L
Duration:
46 h
pH:
4
Temp.:
70 °C
Initial conc. measured:
ca. 10 mg/L
Number of replicates:
Triplicates
Positive controls:
no
Negative controls:
no

Results and discussion

Transformation products:
no
Details on hydrolysis and appearance of transformation product(s):
Hydrolysis measures as a loss of UL125
Dissipation DT50 of parent compoundopen allclose all
pH:
4
Temp.:
50 °C
Hydrolysis rate constant:
0 s-1
DT50:
110 h
pH:
4
Temp.:
60 °C
Hydrolysis rate constant:
0 s-1
DT50:
35.5 h
pH:
4
Temp.:
70 °C
Hydrolysis rate constant:
0 s-1
DT50:
15.5 h

Any other information on results incl. tables

Test 1:

See tables in attached background material

The log10 of the concentration was plotted against time and a straight line achieved with an r^2 value of 0.99895 indicating that the hydrolysis reaction of UL125 was pseuedo-first order.

pH measurements were taken during the course of the test and indicated that the pH of the buffered solution did not alter of the period of the test. Tempareture measurements remained within satisfactory limits throughout the test and ranged from 49.9 to 40 degrees centigrade.

Test 2:

See tables in attached background material

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
the rate of hydrolysis of UL125 has been determined and the half-life (t 1/2) at 25oC has been estimated to be 1856 at pH4.