Reaction mass of 3-[3-(2,3-dihydroxypropoxy)-2-hydroxypropoxy]propane-1,2-diol and 3-(2,3-dihydroxypropoxy)propane-1,2-diol and 3-[3-[3-(2,3-dihydroxypropoxy)-2-hydroxypropoxy]-2-hydroxypropoxy]propane-1,2-diol

Hydrolysis

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 guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

Deviations:

no

Test guideline 2

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

Test material information

Constituent 1

Reference substance name:

1-(1,3-dihydroxypropoxy)propane-1,3-diol; 3-{3-[3-(2,3-dihydroxypropoxy)-2-hydroxypropoxy]-2-hydroxypropoxy}propane-1,2-diol; nonane-1,2,4,5,6,8,9-heptol

EC Number:

915-741-3

Cas Number:

25618-55-7

Molecular formula:

not applicable - multi-constituent substance

IUPAC Name:

1-(1,3-dihydroxypropoxy)propane-1,3-diol; 3-{3-[3-(2,3-dihydroxypropoxy)-2-hydroxypropoxy]-2-hydroxypropoxy}propane-1,2-diol; nonane-1,2,4,5,6,8,9-heptol

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 compound

Dissipation DT50 of parent compound 1

Key result

pH:

4

Temp.:

25 °C

DT50:

> 1 yr

Dissipation DT50 of parent compound 2

Key result

pH:

7

Temp.:

25 °C

DT50:

> 1 yr

Dissipation DT50 of parent compound 3

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.