Registration Dossier

Administrative data

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From 26 September 2006 to 13 December 2006
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: OECD Guideline study perfomed with GLP

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2007
Report Date:
2007

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
Details on test material:
- Name of test material (as cited in study report): methyI 3-oxo-2-pentylcyclopentane acetate
- Substance type: pure active substance
- Physical state: clear, colourless liquid
- Analytical purity: 99.74 % (sum of two isomers and a few position isomers)
- Composition of test material, percentage of components:
- Lot/batch No.: 6202573
- Expiration date of the lot/batch: Sep 03, 2009
- Storage condition of test material: Approximately 4°C, in the dark
- Other:
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
Not applicable
Radiolabelling:
no

Study design

Analytical monitoring:
yes
Buffers:
pH 4: Potassium hydrogen phtalate 0.01 [M]
pH 7: Disodium hydrogen orthophosphate (anhydrous) 0.006 [M], Potassium dihydrogen orthophosphate 0.004 [M], NaCl 0.004 [M]
pH 9: Disodium tetraborate 0.002 [M], NaCl 0.004 [M]

Buffer solutions were filtered trough a 0.2 um membrane filter to ensure they were sterile before the commencement of the test. Also these solutions were subjected to ultrasonication and degassing with nitrogen to minimise dissolved oxygen content.
Details on test conditions:
TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: stoppered glass flasks
- Sterilisation method: 0.2 um sterile membrane filtration
- Lighting: no
- Measures taken to avoid photolytic effects: shielding from light
- Measures to exclude oxygen: ultrasonication and degasing with nitrogen

TEST MEDIUM
- Kind and purity of water: sterile reagent grade water
- Identity and concentration of co-solvent: 1% acetonitrile
Duration of testopen allclose all
Duration:
120 h
pH:
4
Temp.:
50 °C
Initial conc. measured:
189 mg/L
Duration:
120 h
pH:
7
Temp.:
50 °C
Initial conc. measured:
192 mg/L
Duration:
48 h
pH:
9
Temp.:
50 °C
Initial conc. measured:
185 mg/L
Duration:
48 h
pH:
9
Temp.:
50 °C
Initial conc. measured:
195 mg/L
Duration:
70 h
pH:
9
Temp.:
40 °C
Initial conc. measured:
196 mg/L
Duration:
384 h
pH:
9
Temp.:
20 °C
Initial conc. measured:
197 mg/L
Number of replicates:
2
Positive controls:
no
Negative controls:
no
Statistical methods:
None

Results and discussion

Preliminary study:
Preliminary studies performed at pH4, pH7 and pH9 at 50°C indicated that the test material is stable at pH4 and pH 7. (Less than 10% hydrolysis after 5 days at 50°C, equivalent to a half life greater than 1 year at 25°C). The extent of hydrolysis after 48hours at 50°C (>90% hydrolysis) indicated that further testing conducted at 20, 40 and 50°C were required to estimate the rate constant and half-life.
Test performance:
Arrhenius plot was constructed using data of testing conducted at 20, 40 and 50°C; half life at 25°C was estimated from this graph (see attached background material).
Transformation products:
not measured
Identity of transformation productsopen allclose all
No.:
#1
Reference
Reference substance name:
Unnamed
Inventory number:
InventoryMultipleMappingImpl [inventoryEntryValue=EC 222-687-8]
IUPAC name:
(3-oxo-2-pentylcyclopentyl)acetic acid
CAS number:
3572-64-3
No.:
#2
Reference
Reference substance name:
Unnamed
Inventory number:
InventoryMultipleMappingImpl [inventoryEntryValue=EC 200-659-6]
IUPAC name:
methanol
CAS number:
67-56-1
Details on hydrolysis and appearance of transformation product(s):
Experimental identification of transformation products was deem unecessary since the substance wich is a simple methyl ester undergoes a basic hydrolysis. The substance degrades into the corresponding acod and alcohol. Both substances are not classified for the environment in Annex I of Directive 67/548/EEC.
Total recovery of test substance (in %)open allclose all
% Recovery:
101
pH:
4
Temp.:
50 °C
Duration:
48 h
% Recovery:
89.9
pH:
4
Temp.:
50 °C
Duration:
120 h
% Recovery:
92.7
pH:
7
Temp.:
50 °C
Duration:
120 h
% Recovery:
4.9
pH:
9
Temp.:
50 °C
Duration:
48 h
% Recovery:
10.2
pH:
9
Temp.:
50 °C
Duration:
48 h
% Recovery:
25.4
pH:
9
Temp.:
40 °C
Duration:
70 h
% Recovery:
46.2
pH:
9
Temp.:
20 °C
Duration:
382 h
Dissipation DT50 of parent compoundopen allclose all
pH:
4
Temp.:
50 °C
DT50:
>= 1 yr
Type:
not specified
Remarks on result:
other: Preliminary test at pH 4
pH:
7
Temp.:
50 °C
DT50:
>= 1 yr
Type:
not specified
Remarks on result:
other: preliminary test at pH 7
pH:
9
Temp.:
50 °C
DT50:
< 1 yr
Type:
not specified
Remarks on result:
other: Preliminary test at pH 9. Result indicate that further testing is required at this pH (20, 40 and 50 °C, see below)
pH:
9
Temp.:
50 °C
Hydrolysis rate constant:
1.15 d-1
DT50:
14.4 h
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: r= -0.998 (See Attached bacckgroud material)
pH:
9
Temp.:
40 °C
Hydrolysis rate constant:
ca. 0.46 d-1
DT50:
36.5 h
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: r= -0.993 (See "Attached backgroud material")
pH:
9
Temp.:
20 °C
Hydrolysis rate constant:
ca. 0.05 d-1
DT50:
335 h
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: r= -0.996 (See "Attached backgroud material")
pH:
9
Temp.:
25 °C
Hydrolysis rate constant:
ca. 0.09 d-1
DT50:
187 h
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: Extrapolated result for 25 °C; half life = 7.80 days or 187 hours (r= 1, See "Attached backgroud material")
Other kinetic parameters:
None
Details on results:
TEST CONDITIONS
- pH, sterility, temperature, and other experimental conditions maintained throughout the study: Yes

PATHWAYS OF HYDROLYSIS
- Description of pathways: Material is a simple ester that undergoes basic hydrloysis (hydrolysis to the carboxylic acid and corresponding alcohol)
- Figures of chemical structures attached: No

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The test material did not show significant hydrolysis at 25°C in acidic or neutral conditions (half life > 1 year at pH 4 and 7) , however a significant hydrolysis occured in basic conditions (half life: 7.8 days at pH 9). Transformation products are the corresponding acid and methanol. Both substances are not classified for the environment in Annex I of Directive 67/548/EEC.
Executive summary:

Methods.The hydrolysis of the test material was determined according the OECD TG111 : Hydrolysis as a function of pH.

The guideline covers the extreme and typical environmental pHs.

Briefly, 200 mg/l sterile sample solutions at pH 4, 7 and 9 were maintained at 50.0 ± 0.5°C using 1% acetonitrile as co-solvent. The solutions were shielded from light and were subjected to ultrasonication and degassing with nitrogen before the commencement of the test to minimize dissolved oxygen content. All test conditions including standard solutions were performed in duplicate. The concentrations of the sample solutions were determined by Gas Chromatography using a validated method (>98% recovery).

 

Results and conclusions. A preliminary testing indicated that the test material did not show significant hydrolysis in acidic or neutral conditions (half life > 1 year at pH 4 and pH 7) but indicated that a significant hydrolysis occurred in basic conditions. The extent of hydrolysis after 48 hours indicated that further tests (Tier 2), conducted at 20, 40 and 50 °C, were required to estimate the rate constant and half-life. Half life value of the test material at 25 °C was extrapolated from the former values using the Arrhenius plot.

 

pH

Rate constant (s-1)

Estimated half-life at 25°C

4
7

-

-

> 1 year

> 1 year

9

1.03 x 10-6

7.80 days

 

The test material did not show significant hydrolysis in acidic or neutral conditions; however a significant hydrolysis occurred in basic conditions. Experimental identification of hydrolysis products was considered unnecessary since the test material was a simple ester that undergoes basic hydrolysis. The test material had degraded to leave the carboxylic acid (3-oxo-2-pentylcyclopentyl)acetic acid, and methanol. Both substances are not classified for the environment in Annex I of Directive 67/548/EEC.