Registration Dossier

Administrative data

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
December 18, 2013 - July 17, 2014
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The study was performed in accordance with OECD guideline 111. Non-GLP study.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2014
Report Date:
2014

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Version / remarks:
(2004)
GLP compliance:
no
Remarks:
non GLP study

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Remarks:
migrated information: powder
Details on test material:
Name of test material (as cited in study report): Disodium Isodecyl Sulfosuccinate
Description: white powder
Storage conditions of test material: at room temperature in well-sealed container
The substance was tested as received.
Radiolabelling:
no

Study design

Analytical monitoring:
yes
Details on sampling:
A sample (5 mL) was taken and diluted to 10.0 mL with methanol in a volumetric flask. The resulting solution was shaken well before HPLC analysis. Blank buffer solutions and standard solutions were treated in the same way.
Buffers:
pH 4 buffer solution - potassium acid phthalate
pH 7 buffer solution - potassium phosphate monobasic and sodium hydroxide, chlorine titrimeter reagent
pH 9 buffer solution - boric acid, potassium chloride, and sodium hydroxide

The buffers were filtered through a 0.1 µm syringe filter and degassed by ultrasonication.
Details on test conditions:
-Tier 1 preliminary test at pH 4, 7 and 9 and 50°C
-Tier 2 main study at pH 9 and 65°C, 50°C and 20°C
-The test solutions were incubated in a liquid bath or incubator in the dark at the specific test temperature (± 0.5°C).
-Each sample was injected in triplicate into the HPLC system.
-All equipment and glassware was sterilized.

Details Tier 1 preliminary test
-Test substance solutions were prepared (in duplicate) in the buffer solutions pH 4, 7 and 9 at concentrations ranging from 2.9 and 3.5 g/L.
-Samples were taken from the test substance solutions after 120 h incubation at 50°C.
-Standards were prepared in buffer solution pH 4, 7 and 9 at a concentration of 3 g/L.
-The standards were treated in the same way as the test samples (see Details on sampling).
-The mean (n=3) peak area of each standard or sample was multiplied by the correction factor '3.0/concentration prepared' (see table below) in order to be able to compare the peak areas of the samples with the standards and to calculate the '% of mean initial concentration'.

Details Tier 2 main study
-Test substance solutions were prepared at nominal 3 g/L (two solutions per test temperature).
-Samples were taken from the test substance solution after preparation and after 15, 24, 46, 66, 72, 139 and 216 h of incubation at 65°C.
-Samples were taken from the test substance solution after preparation and after 15, 24, 46, 72, 139, 216 h and 689.5 h of incubation at 50°C.
-Samples were taken from the test substance solution after preparation and after 48, 196, 263, 426.5 h, 719 h and 744 h of incubation at 20°C.
-On each day of analysis standards were prepared in buffer solution pH 9 at a concentration of 3 g/L.
-The standards were treated in the same way as the test samples (see Details on sampling).
-The mean (n=3) peak area of each standard or sample was multiplied by the correction factor '3.0/concentration prepared' (see table below).
-The % peak area relative to the peak area of the fresh standard was calculated (=% of mean initial concentration) (see table below).
-Ct=Concentration at time t = 3.0 x '% of mean of initial concentration' (see table below).
Duration of testopen allclose all
Duration:
216 h
pH:
9
Temp.:
65 °C
Initial conc. measured:
2.99 - 3.01 g/L
Duration:
689.5 h
pH:
9
Temp.:
50 °C
Initial conc. measured:
2.99 - 3.01 g/L
Duration:
744 h
pH:
9
Temp.:
20 °C
Initial conc. measured:
2.99 - 3.02 g/L
Number of replicates:
two (A and B)
Positive controls:
no
Negative controls:
no

Results and discussion

Preliminary study:
At pH 4 and pH 7, hydrolysis < 10% was observed after 5 days. This corresponds with a half-life time at 25°C of > 1 year (half-life time at 25°C is > 1 year). According to the guideline, no further tests were required at pH 4 and pH 7.

A degree of > 10% of hydrolysis was observed after 5 days at pH 9 and 50°C. In accordance with the guideline, a Tier 2 test was performed at pH 9.
Transformation products:
not measured
Details on hydrolysis and appearance of transformation product(s):
In general carboxylic esters hydrolyze to the carboxylic acid and an alcohol. Proposed hydrolysis product: Sulphonatosuccinate anion; C4H5O7S.
Dissipation DT50 of parent compoundopen allclose all
pH:
9
Temp.:
65 °C
Hydrolysis rate constant:
0.013 h-1
DT50:
53.8 h
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: y= -0.0129x + 1.0064; r2=0.9905
pH:
9
Temp.:
50 °C
Hydrolysis rate constant:
0.003 h-1
DT50:
226.5 h
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: y= -0.00306+1.0692;r2=0.9984
pH:
9
Temp.:
20 °C
Hydrolysis rate constant:
0 h-1
DT50:
5 338 h
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: Y= -0.00013x + 1.1322; r2=0.5396
pH:
9
Temp.:
25 °C
Hydrolysis rate constant:
0 h-1
DT50:
2 874.6 h
Type:
other: from the Arrhenius plot
Remarks on result:
other: t1/2= 120 days
Details on results:
No significant peaks were observed at the approximate retention time of the test substance on analysis of any matrix blank solutions.




Any other information on results incl. tables

Table: Results of the preliminary (Tier 1) test at pH 4, 7 and 9 at 50°C

pH

Solution

Concentration

prepared (g/L)

Mean (n=3) peak area

Corrected peak area

% of Mean Initial Concentration

4

Standard A

3.4

786.6

684.0

100

Sample 1 (120 h)

3.0

726.3

719.1

105.1

Sample 2 (120 h)

2.9

692.9

729.4

106.6

7

Standard B

3.5

795.9

684.2

100

Sample 3 (120 h)

3.5

796.3

692.5

101.2

Sample 4 (120 h)

3.3

796.7

715.6

104.6

9

Standard C

3.0

670.2

667.9

100

Sample 5 (120 h)

3.0

485.6

482.4

72.2

Sample 6 (120 h)

3.2

509.0

465.6

69.7

Table: Tier 2 results of the test at pH 9 and 65°C

Solution

Mean (n=3) peak area

Corrected peak area

% of Mean Initial Concentration

Initial sample A, 3.01 mg/mL

1061.7

1055.9

 

Initial sample B, 2.99 mg/mL

1085.3

1088.4

 

Standard 1, 3.02 mg/mL

1041.6

1033.3

 

15 hrs, sample A

807.9

803.5

77.8

15 hrs, sample A

805.8

808.1

78.2

24 hrs, sample A

714.1

710.2

68.7

24 hrs, sample B

716.8

718.8

69.6

Standard 2, 3.02 mg/mL

1017.9

1009.9

 

46 hrs, sample A

504.8

502.0

49.7

46 hrs, sample B

588.6

590.2

58.4

Standard 3, 3.02 mg/mL

996.9

990.3

 

66 hrs, sample A

364.1

362.1

36.6

66 hrs, sample B

364.2

365.3

36.9

72 hrs, sample A

349.3

347.4

35.1

72 hrs, sample B

339.2

340.2

34.4

Standard 4, 3.04 mg/mL

1017.8

1004.4

 

139 hrs, sample A

137.2

136.1

13.6

139 hrs, sample B

130.8

130.4

13.1

Standard 5, 3.00 mg/mL

1006.9

1005.6

 

216 hrs, sample A

59.8

59.3

5.9

216 hrs, sample B

65.8

65.5

6.6

Table: Tier 2 results of the test at pH 9 and 50°C

pH 9 Buffer Solution

Mean (n=3) peak area

Corrected peak area

% of Mean Initial Concentration

Initial sample A, 3.01 mg/mL 

1061.7

1055.9

 

Initial sample B, 2.99 mg/mL 

1085.3

1088.4

 

Standard 1, 3.02 mg/mL

1041.6

1033.3

 

15 hrs, sample A

989.1

983.7

95.2

15 hrs, sample A

975.2

977.9

94.6

24 hrs, sample A

929.9

924.8

89.5

24 hrs, sample B

944.0

946.7

91.6

Standard 2, 3.02 mg/mL

1017.9

1009.9

 

46 hrs, sample A

876.1

871.3

86.3

46 hrs, sample B

868.1

870.5

86.2

Standard 3, 3.02 mg/mL

996.9

990.3

 

72 hrs, sample A

776.2

772.0

78.0

72 hrs, sample B

739.7

741.8

74.9

Standard 4, 3.04 mg/mL

1017.8

1004.4

 

139 hrs, sample A

634.3

628.9

62.6

139 hrs, sample B

636.3

634.2

63.1

Standard 5, 3.00 mg/mL

1006.9

1005.6

 

216 hrs, sample A

505.8

503.1

50.0

216 hrs, sample B

471.6

472.9

47.0

Standard 7, 3.03 mg/mL

931.6

921.8

 

689.5 hrs, sample A

113.8

113.2

12.3

689.5 hrs, sample B

106.1

106.4

11.5

Table: Tier 2 results of the test at pH 9 and 20°C

pH 9 Buffer Solution

Mean (n=3) peak area

Corrected Peak area 

% of Mean Initial Concentration

Initial sample C, 2.99 mg/mL

959.2

960.6

 

Initial sample D 3.02 mg/mL

993.2

993.7

 

Standard 8, 3.05 mg/mL

948.2

932.0

 

48 hrs, sample C

923.8

925.2

99.3

48 hrs, sample D

980.5

981.0

105.3

Standard 9, 3.07 mg/mL

893.4

873.6

 

196 hrs, sample C

877.4

878.7

100.6

196 hrs, sample D

930.1

930.6

106.5

Standard 10, 3.04 mg/mL

965.2

952.5

 

263 hrs, sample C

909.5

910.8

95.6

263 hrs, sample D

955.6

956.1

100.4

Standard 11, 3.06 mg/mL

936.6

918.2

 

263 hrs, sample C

873.4

874.7

95.3

263 hrs, sample D

911.5

912.0

99.3

Standard 12, 3.07 mg/mL

976.4

954.8

 

426.5 hrs, sample C

902.8

904.1

94.7

426.5 hrs, sample D

938.9

939.4

98.4

Standard 13, 2.98 mg/mL

948.1

953.2

 

719 hrs, sample C

881.3

882.6

92.6

719 hrs, sample D

936.7

937.2

98.3

Standard 14, 3.03 mg/mL

1002.1

991.5

 

744 hrs, sample C

895.7

897.0

90.5

744 hrs, sample D

944.6

945.1

95.3

Table: Tier 2 results at pH 9 and 65°C

t

[h]

lnCt (Ct in g/L)

15

0.85

15

0.85

24

0.72

24

0.74

46

0.40

46

0.56

66

0.09

66

0.10

72

0.05

72

0.03

139

-0.90

139

-0.94

216

-1.73

216

-1.63

Table:  Tier 2 results at pH 9 and 50°C

t

[h]

lnCt (Ct in g/L)

15

1.05

15

1.04

24

0.99

24

1.01

46

0.95

46

0.95

72

0.85

72

0.81

139

0.63

139

0.64

216

0.41

216

0.34

689.5

-1.00

689.5

-1.06

Table: Tier 2 results at pH 9 and 20°C

t

[h]

lnCt (Ctin g/L)

48

1.09

48

1.15

196

1.10

196

1.16

263

1.05

263

1.10

426.5

1.05

426.5

1.09

575

1.04

575

1.08

719

1.02

719

1.08

744

1.00

744

1.05

Applicant's summary and conclusion

Conclusions:
The substance is hydrolytically stable at pH 4 and 7 (half-life time at 25°C of > 1 year). Hydrolysis of the test substance at pH 9 shows a pseudo-first order behaviour. Half-life time at 25°C and pH 9 was determined to be 120 days.
Executive summary:

The rate of hydrolysis of the substance at pH values normally found in the environment (pH 4-9) was determined in a OECD TG 111 study. At pH 4 and 7, a degree of < 10% of hydrolysis was observed after 5 days at 50 °C. This corresponds with a half-life time at 25°C of > 1 year. The substance can be considered hydrolytically stable at pH 4 and 7.

 

At pH 9 and 50°C, a degree of ca. 30% of hydrolysis was observed after 5 days and therefore a Tier 2 study was performed at pH 9. Hydrolysis rates of the substance at 65, 50 and 20°C were determined from which the hydrolysis rate at 25°C was calculated. The test substance was shown to degrade by a pseudo-first order behaviour. Half-life time at 25°C and pH 9 was determined to be 120 days.