Registration Dossier

Administrative data

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
24 October 1996 - 29 January 1997
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study conducted to GLP in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1997
Report Date:
1997

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
Deviations:
no
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: solid
Details on test material:
MMBC
Appearance: light brown solid
Storage conditions: room temperature
Radiolabelling:
no

Study design

Analytical monitoring:
yes
Details on sampling:
Samples taken for analysis at 0 and 15 minutes.

The solution was bottled for analysis by G.C.
Buffers:
PREPARATION OF BUFFER SOLUTIONS
pH 4 buffer
Potassium dihydrogen citrate (23.00 g) was dissolved in distilled water (900 mL) and the pH of the solution adjusted to ca 4 with 1M aqueous sodium hydroxide at ambient temperature. The solution was then diluted to 1000 mL with distilled water and again adjusted to pH 4.00. This solution was stirred and heated on a magnetic stirrer/hotplate and the pH measured as 4.00 with the temperature of the buffer solution at 25 °C ± 0.5 °C.

pH 7 buffer
Potassium dihydrogen orthophosphate (13.61 g) was dissolved in distilled water (900 mL) and the pH of the solution adjusted to ca 7 with 1M aqueous sodium hydroxide at ambient temperature.. The solution was then diluted to 1000 mL with distilled water and again adjusted to pH 7.00. This solution was stirred and heated on a magnetic stirrer/hotplate and the pH measured as 7.01 with the temperature of the buffer solution at 25 °C ± 0.5 °C.

pH 9 buffer
Potassium chloride (7.46 g) and boric acid (6.20 g) were dissolved in distilled water (900 mL) and the pH of the solution adjusted to ca 9 with 1M aqueous sodium hydroxide at ambient temperature. The solution was then diluted to 1000 mL with distilled water and again adjusted to pH 9.01. This solution was stirred and heated on a magnetic stirrer/hotplate and the pH measured as 9.01 with the temperature of the buffer solution at 25 °C ± 0.5 °C.


PREPARATION OF STOCK SPIKING SOLUTION
Test substance (1.00352 g) was accurately weighed into a 100 mL volumetric flask, dissolved in and diluted to volume with acetone to produce a 10035 µg/mL solution.
Details on test conditions:
PREPARATION OF CALIBRATION SOULTIONS
Test substance (0.10756 g) was accurately weighed into a 100 mL volumetric flask, then dissolved in and diluted to volume with dichloromethane. This solution was further diluted with dichloromethane to produce calibration standards in the range 53.780 µg/mL to 268.90 µg/mL.

PERFORMANCE OF THE TEST
0 hour sample preparation and analysis
The buffer solutions were autoclaved at 122 °C for 17 minutes and then purged with nitrogen for 15 minutes prior to use.
Dichloromethane (10 mL) was transferred to a 250 mL separating funnel, and spiked using 200 µL of the stock spiking solution. The appropriate buffer (100 mL) was then added to the separating funnel and the contents were then shaken for 5 seconds. The dichloromethane layer was then passed through a cotton wool/sodium sulphate plug (pre-rinsed and dried with dichloromethane) into a glass vial. An aliquot of this solution was immediately bottled for analysis by G.C.

15 minute sample preparation and analysis
Buffer solution (pH 4, 7 or 9) ca 100 mL was transferred into a volumetric flask (100 mL). Stock spiking solution (200 µL) was added and the solution diluted to volume with the appropriate buffer solution which was then placed in a 25 °C water bath. The flasks were tightly stoppered and covered in aluminium foil to exclude daylight. After 15 minutes, the solution was removed from the water bath. The contents of the volumetric flask were transferred to a 250 mL separating funnel containing dichloromethane (10 mL) and shaken for 5 seconds. The dichloromethane layer was passed through a cotton wool/sodium sulphate plug as for the 0 hour analysis and the solution was immediately bottled for analysis by gas chromatography.

BLANK TESTS
Buffer solution (one at each pH) was transferred into a separating funnel (250 mL) containing dichloromethane (10 mL). The contents were shaken for 5 seconds and the dichloromethane layer was passed through a cotton wool/sodium sulphate plug (pre-rinsed and dried with dichloromethane). An aliquot of this solution was immediately bottled for analysis by gas chromatography.

CALCULATION
The peak response of test substance in each calibration standard chromatogram was measured and calibration curves constructed by linear regression of standard response versus standard concentration. The response of the peaks observed at the characteristic retention times for one test substance in sample chromatograms was measured and the concentration of the test substance was determined using the equation below:

Y =I + Sx (regression equation)

Tests
Concentration (µg/mL)= (Y - I) / S
where Y = integrated peak of sample chromatogram
x = concentration of calibration standard (µg/mL)
I = intercept derived from linear regression of calibration data
S = slope derived from linear regression of calibration data
Duration of testopen allclose all
Duration:
15 min
pH:
4
Temp.:
25 °C
Initial conc. measured:
23.413 - 25.393 other: µg/mL
Duration:
15 min
pH:
7
Temp.:
25 °C
Initial conc. measured:
24.569 - 26.554 other: µg/mL
Duration:
15 min
pH:
9
Temp.:
25 °C
Initial conc. measured:
25.074 - 25.77 other: µg/mL
Number of replicates:
two per pH tested
Positive controls:
no
Negative controls:
no

Results and discussion

Transformation products:
not measured
Dissipation DT50 of parent compoundopen allclose all
pH:
4
Temp.:
25 °C
DT50:
< 1 d
pH:
7
Temp.:
25 °C
DT50:
< 1 d
pH:
9
Temp.:
25 °C
DT50:
< 1 d
Details on results:
Calibration data provided a slope of 632.44, an intercept of -16379 and a correlation coefficient of 0.99297 showing detector response to be linear in the concentration range employed.

Under the test conditions the test substance was found to undergo hydrolysis, at pH 4, 7 and 9 at 25 °C. At pH 4, 9.2 % (mean of 0% and 18.3 %) remained, at pH 7, 7.4 % (mean of 0 % and 14.7 %) and at pH 9, 7.6 % (mean of 0 % and 15.1 %) remained. Analytical data is shown in Table 1.

There was no observable peak at the retention time of the test substance in the blanks.

Although relatively high values were obtained for the t = 0 hour samples, the results clearly show that rapid hydrolysis occurred resulting in greater than 80% hydrolysis at each pH at 25 °C in 15 minutes.

The half-life at 25 °C can be estimated as less than 1 day at pH 4, 7 and 9.

Any other information on results incl. tables

Table 1 Analytical Data

Time-point

pH

Duplicate

Integrated Peak Area

Analysed Concentration (µg/mL)

Nominal Concentration (µg/mL)

Analysed Concentration expressed as a percentage of Nominal Concentration

0 hours

4

4

7

7

9

9

A

B

A

B

A

B

131695

144217

139007

151561

142197

146602

23.413

25.393

24.569

26.554

25.074

25.770

20.070

20.070

20.070

20.070

20.070

20.070

116.7

126.5

122.4

132.3

124.9

128.4

15 minutes

4

4

7

7

9

9

A

B

A

B

A

B

6859

NOP

NOP

2260

NOP

2784

3.6744

-

-

2.9472

-

3.0301

20.070

20.070

20.070

20.070

20.070

20.070

18.3

-

-

14.7

-

15.1

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
Under the conditions of the study, the test substance was found to undergo greater than 80% hydrolysis at 25 °C and at pH 4, 7 and 9. Therefore the half life at 25 °C can be estimated to be less than 1 day at pH 4, 7 and 9.
Executive summary:

The rate of hydrolysis of the test substance was determined at three pH values in accordance with the standardised guideline EU Method C.7. After 15 minutes at 25 ºC more than 80% of the test substance had hydrolysed in all of the investigated pH values. In accordance with the test method used, the half-life time t½ of the test substance can be estimated to be:

t½ < 1 day at 25 ºC and pH 4

t½ < 1 day at 25 ºC and pH 7

t½ < 1 day at 25 ºC and pH 9