Registration Dossier

Administrative data

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
07 July - 21 October 2009
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study was performed according to OECD and EC guidelines and according to GLP principles.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2009
Report date:
2009

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
Deviations:
no
GLP compliance:
yes

Test material

Constituent 1
Chemical structure
Reference substance name:
Reaction mass of [ 1,​2-​Propanediol, 3,​3'-​oxybis- ] and [ 1,​2-​Propanediol, 3,​3'-​[(2-​hydroxy-​1,​3-​propanediyl)​bis(oxy)​]​bis- ] and [ 1,​2-​Propanediol, 3,​3'-​[oxybis[(2-​hydroxy-​3,​1-​propanediyl)​oxy]​]​bis- ]
EC Number:
915-741-3
Molecular formula:
not applicable - multi-constituent substance
IUPAC Name:
Reaction mass of [ 1,​2-​Propanediol, 3,​3'-​oxybis- ] and [ 1,​2-​Propanediol, 3,​3'-​[(2-​hydroxy-​1,​3-​propanediyl)​bis(oxy)​]​bis- ] and [ 1,​2-​Propanediol, 3,​3'-​[oxybis[(2-​hydroxy-​3,​1-​propanediyl)​oxy]​]​bis- ]
Constituent 2
Reference substance name:
Polyglycerol-3
IUPAC Name:
Polyglycerol-3
Details on test material:
- Name of test material (as cited in study report): Polyglycerol-3
- Substance type: organic liquid
- Physical state: Colourless to pale yellow viscous liquid
- Analytical purity:
27.9% Diglycerol
46.0% Triglycerol
17.9% Tetraglycerol
5.6% Pentaglycerol
2.6% Hexaglycerol and higher
- Purity test date: no data
- Lot/batch No.: RBA081008A
- Expiration date of the lot/batch: 31 May 2010
- Stability under test conditions: stabile
Radiolabelling:
no

Study design

Analytical monitoring:
yes
Details on sampling:
For each sampling time, duplicate sterile vessels under vacuum were filled with 6 ml test solution and placed in the dark in a temperature controlled environment at 50.0°C +/- 0.2°C.
Buffers:
Buffer solutions
Acetate buffer pH 4, 0.1 M solution of 16.6% 0.1 M sodium acetate and 83.4% 0.1 M acetic acid containing 0.0009% (w/v) sodium azide.

Phosphate buffer pH 7, 0.1 M solution of 0.1 M potassium dihydrogenphosphate adjusted to pH 7 using 10 N sodium hydroxide containing 0.0009% (w/v) sodium azide.

Borate buffer pH 9, 0.1 M solution of 0.1 M boric acid and 0.1 M potassium chloride adjusted to pH 9 using 10 N sodium hydroxide containing 0.0009% (w/v) sodium azide.
Details on test conditions:
The rate of hydrolysis of the test substance as a function of pH was determined at pH values normally found in the environment (pH 4-9).
 
Preliminary test - Tier 1
Test substance solutions were prepared in the buffer solutions at a target concentration of 500 mg/l. Each solution was filter-sterilised through a 0.2µm FP 30/0.2 CA-S filter (Whatman, Dassel, Germany) and transferred into a sterile vessel. To exclude oxygen, nitrogen gas was purged through the solution for 5 minutes. For each sampling time, duplicate sterile vessels under vacuum were filled with 6 ml test solution and placed in the dark in a temperature controlled environment at 50.0°C±0.2°C.
 
The concentration of the test substance in the test samples was determined immediately after preparation (t=0) and after 5 days. The samples taken at t=5 days were cooled to room temperature using running tap water. The samples were first diluted by a factor of 10 with water and thereafter by a factor of 10 with acetonitrile. The latter dilution was analysed.
 
Blank buffer solutions were treated similarly as the test samples and analysed at t=0.
The pH of each of the test solutions (except for the blanks) was determined at each sampling time.
 
Main study - Tier 2
Test samples were prepared and treated similarly as during the preliminary test.
 
The concentrations of the test substance based on response of triglycerol, were determined immediately after preparation (t=0) and at several sampling points after t=0. Blank buffer solutions were treated similarly as the test samples and analysed at t=0.
 
The pH of each of the test solutions (except for the blanks) was determined.
The study was performed at 49.9°C±0.2°C.
Duration of test
Duration:
214.5 h
Temp.:
50
Initial conc. measured:
ca. 500 mg/L
Number of replicates:
Calibration solutions were injected in duplicate. Test samples were analysed by single injection.
Positive controls:
yes
Remarks:
acetonitrile/water
Negative controls:
yes
Remarks:
buffer solutions
Statistical methods:
During the preliminary test, calibration curves was constructed excluding two data points at
0.08 mg/l since the response factor was significantly different from the response factor of the other data points. Linear regression analysis was performed using the least squares method with a 1/concentration2 weighting factor. The coefficient of correlation (r) was > 0.99 for each curve.

Results and discussion

Preliminary study:
Diglycerol
Based on analysis at m/z 167.0 amu (diglycerol), a degree of hydrolysis of < 10% was observed after 5 days at pH 4, pH 7 and pH 9. It demonstrated that the half-life time of diglycerol at 25°C is > 1 year. According to the guideline, no further tests were required.

Triglycerol
Based on analysis at m/z 241.0 amu (triglycerol), a degree of hydrolysis of < 10% was observed after 5 days at pH 4 and pH 7. It demonstrated that at these pH’s, the half-life time of triglycerol at 25°C is > 1 year. According to the guideline, no further tests were required.

At pH 9, a degree of hydrolysis of ≥ 10% after 5 days was observed. According to the guideline, the higher Tier test was required to determine the half-life time of triglycerol.

The mean recoveries of the buffer solutions fell within the criterion range of 90-110%. It demonstrated that the analytical method was adequate to support the hydrolysis study on the test substance.
Test performance:
No test substance was detected in the blank buffer solutions.
Transformation products:
not measured
Details on hydrolysis and appearance of transformation product(s):
For triglycerol, the main study was performed at pH 9. Analysis was performed at m/z 241.0 amu. No test substance was detected in the blank buffer solutions.

The mean recovery fell slightly outside the criterion range of 90-110% but it was still within the range 70-110% and therefore accepted.

The results showed that over the 120-hours period between 94.5 and 214.5 hours, the Polyglycerol-3 concentration based on the response of triglycerol had not decreased by more than 10%. Based on this, it was concluded that the half-life time of triglycerol at pH 9 and at 25°C is > 1 year. Therefore, no further tests were performed.
Total recovery of test substance (in %)
% Recovery:
84
pH:
9
Temp.:
50 °C
Duration:
214.5 h
Dissipation DT50 of parent compoundopen allclose all
Key result
pH:
4
Temp.:
25 °C
DT50:
> 1 yr
Key result
pH:
7
Temp.:
25 °C
DT50:
> 1 yr
Key result
pH:
9
Temp.:
25 °C
DT50:
> 1 yr
Details on results:
see below

Any other information on results incl. tables

Main test – hydrolysis of triglycerol at 50°C

Sampling time

 


[hours]

Analysed

Polyglycerol-3concentration

[mg/]

Degree of hydrolysis

Actual pH

0

419

n.a.

9.0

0

416

n.a.

9.1

94.5

394

5.6

9.1

94.5

388

7.0

9.1

214.5

464

-11

9.0

214.5

448

-7.3

9.0

n.a.     Not applicable.

 

Recovery at m/z 241.0 (triglycerol)

Temperature

 

(°C)

Nominal Polyglycerol-3 concentration
[mg/l]

AnalysedPolyglycerol-3concentration
[mg/l]

Recovery


[%]

Mean
recovery

[%]

50

496

419

84

84

 

496

416

84

 

 

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The half-life time of the major constituents in Polyglycerol-3 (i.e. diglycerol and triglycerol) at pH values normally found in the environment (pH 4-9) at 25°C were determined to be:
pH 4 t½ > 1 year
pH 7 t½ > 1 year
pH 9 t½ > 1 year

Based on structural similarity, it is expected that these half-life times also apply for the higher polyglycerol constituents in Polyglycerol-3.