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Hydrolysis

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Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2020
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
Version / remarks:
31. May 2008
Deviations:
yes
Remarks:
The temperature range 50 ± 0.5 °C was not held during the incubation phase. This was considered uncritical because the deviation of the average temperature was small, and the test item showed no signs of degradation at all three pH values.
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Version / remarks:
13. Apr. 2004
Deviations:
yes
Remarks:
The temperature range 50 ± 0.5 °C was not held during the incubation phase. This was considered uncritical because the deviation of the average temperature was small, and the test item showed no signs of degradation at all three pH values.
GLP compliance:
yes (incl. QA statement)
Specific details on test material used for the study:
Batch no.: 170103
Appearance: White crystalline powder
CAS No.: 17625-03-5
EINECS-No.: 241-602-5
Molecular formula: C7H5SO5Na
Molecular weight: 224.17 g/mol
Purity: > 99.0% (Titration with NaOH, Glass indicating electrode, Calomel reference electrode)
Homogeneity: totally homogeneous
Stability: H2O: 96 h; EtOH: unknown; acetone: unknown; CH3CN: unknown; DMSO: unknown
Solubility: H2O: >1 g/L; EtOH: unknown; acetone: unknown; CH3CN: unknown; DMSO: unknown
Expiry date: 14. Feb. 2024
Storage: Room Temperature (20 ± 5°C), keep away from humidity
Radiolabelling:
no
Analytical monitoring:
yes
Buffers:
Water
Deionised water was used for the test item stock solution and for the preparation of the buffer solutions.

pH Buffer Solutions
The following solutions were used unsterile:
Compound Molecular Formula Concentration
Acetic acid CH3COOH 2 M
Sodium acetate CH3COONa 1 M
Sodium hydroxide NaOH 2 M

Buffer-Solutions, pH 4
CH3COOH, 2 M - 16 mL
CH3COONa - 8 mL
Demineralised water ad 200 mL
Final pH value = 4.03

Buffer-Solution, pH 7
KH2PO4 - 1.7430 g
Demineralised water - 50 mL
NaOH, 2 M - 2.98 mL
Demineralised water ad 200 mL
Final pH value (adjusted with NaOH) = 7.01

Buffer-Solution, pH 9
H3BO3 - 0.6193 g
KCl - 0.7465 g
Demineralised water - 100 mL
NaOH, 2 M - 2.15 mL
Demineralised water ad 200 mL
Final pH value (adjusted with NaOH) = 9.04
Estimation method (if used):
Not used.
Details on test conditions:
Glass Material
All glassware was sterilized before use.
Vials with PTFE septa were used. A large head space above the liquid was avoided.

Incubation Chamber
Memmert Tv30u

Instruments and Devices
The following instruments and devices were used for the performance of the study:
• Autoclave 3870 ELV-B, Tuttnauer
• pH-Meter pH 540 GLP, wtw
• Analytical scales XS205DU, Mettler Toledo
• Adjustable pipettes with one-way tips, Rainin ®, Mettler Toledo
• Repeater pipettes Autorep E, Mettler Toledo
• Syringe sterile filters, 0.2 µm PTFE
• Carbon analyser TOC multi N/C 2100S, Analytik Jena
• Refrigerator
• Temperature data loggers, ebro
Usage and calibration followed the corresponding SOP in the current edition.
Standard laboratory material (e.g. glassware) was also used in the performance of the study

Analytical Determination
An analytical method using HPLC-UV was validated and is fully described in the valida-tion report VB17042002G926.

Analytical Instrument
Identification: HPLC 6
Components:
- HPLC Ultimate3000:
- Solvent Rack
- Pump LPG-3400SD
- Autosampler WPS-3000TSL
- Column Compartment TCC-3200 with
- 6-fold motorized HPLC valve
- UV-Detector MWD-3000
Manufacturer: Thermo Fisher Scientific
Software: CHROMELEON 6.80 SR15b Build 4981

Usage and calibration followed SOP 11400529 in the current edition.
Duration:
120 h
pH:
4
Temp.:
49.2 °C
Initial conc. measured:
488.53 mg/L
Duration:
120 h
pH:
7
Temp.:
49.3 °C
Initial conc. measured:
524.62 mg/L
Duration:
120 h
pH:
9
Temp.:
49.3 °C
Initial conc. measured:
486.56 mg/L
Number of replicates:
2 for blank at each pH values and 6 for each sample and for each pH value.
Positive controls:
no
Negative controls:
no
Statistical methods:
Not relevant.
Preliminary study:
After five days (120 hours), the concentrations of the test item lay slightly above 100 % of the start concentration at pH values 4 and 9, indicating that the test item is hydrolytically stable. As the starting value of pH 7 was much higher than expected (> 120 % of the nominal concentration) but in the same concentration range as the other two pH values at the end of the incubation period, a sample preparation error at t = 0 was assumed and Tier 1 was repeated for pH 7.
In the repeated experiment at pH 7, the change in test item concentration was + 0.4 % compared to the starting concentration. The test item is considered hydrolytically stable also at pH 7.
Transformation products:
not measured
pH:
4
Temp.:
49.2 °C
Duration:
120 h
Remarks on result:
hydrolytically stable based on preliminary test
pH:
7
Temp.:
49.3 °C
Duration:
120 h
Remarks on result:
hydrolytically stable based on preliminary test
pH:
9
Temp.:
49.2 °C
Duration:
120 h
Remarks on result:
hydrolytically stable based on preliminary test
pH:
4
Temp.:
49.2 °C
Remarks on result:
hydrolytically stable based on preliminary test
pH:
7
Temp.:
49.3 °C
Remarks on result:
hydrolytically stable based on preliminary test
pH:
9
Temp.:
49.2 °C
Remarks on result:
hydrolytically stable based on preliminary test

Tier 1

Measured Concentrations, Decrease

The measured concentrations and the decrease in tier 1 are presented in the following table.

 

Table. Measured Concentrations t = 0 h.

Sample
Name

Peak Area
[mAU*min]

Dilution
Factor

Concentration
[mg/L]

Mean Concentration
[mg/L]

Blank pH 4
t=0 h

n.a.

none

< LOQ

< LOQ

n.a.

none

< LOQ

pH 4 t=0 h

7.1701

50

485.39

488.53

7.2615

50

491.66

Blank pH 7
t=0 h

n.a.

none

< LOQ

< LOQ

n.a.

none

< LOQ

pH 7 t=0 h
t=0 h

8.4491

50

573.19

607.291

8.5520

50

580.25

Blank pH 9
t=0 h

n.a.

none

< LOQ

< LOQ

n.a.

none

< LOQ

pH 9 t=0 h
t=0 h

7.2073

50

487.94

486.56

7.1671

50

485.18

1Including matrix correction factor 1.0530

 

Table. Measured Concentrations t = 0 h, repeated experiment.

Sample
Name

Peak Area
[mAU*min]

Dilution
Factor

Concentration
[mg/L]

Mean Concentration
[mg/L]

Blank pH 7
t=0 h

n.a.

none

< LOQ

< LOQ

n.a.

none

< LOQ

pH 7 t=0 h
t=0 h

5.6604

50

496.95

524.621

5.6890

50

499.48

1Including matrix correction factor 1.0530

  

Table. Measured Concentrations t = 120 h.

Sample Name

Peak Area
[mAU *min]

Concentration
[mg/L]

Dilution
Factor

Mean
Concentration
[mg/L]

Blank pH 41
t = 120 h

n.a.

< LOQ

none

< LOQ

n.a.

< LOQ

none

pH 4
t=120 h1

7.4350

503.57

50

506.05

7.4658

505.69

50

7.5151

509.07

50

7.4219

502.67

50

7.5364

510.53

50

7.4525

504.77

50

Blank pH 7
t = 120 h2

n.a.

< LOQ

none

< LOQ

n.a.

< LOQ

none

pH 7
t=120 h2

7.3407

497.10

50

531.321

7.4791

506.60

50

7.4853

505.17

50

7.3265

496.13

50

7.5673

512.66

50

7.5260

509.82

50

Blank pH 9
t = 120 h3

n.a.

< LOQ

none

< LOQ

n.a.

< LOQ

none

pH 9
t=120 h3

7.5122

508.87

50

499.90

7.3722

499.26

50

7.3495

497.70

50

7.4075

501.69

50

7.3372

496.86

50

7.3102

495.01

50

1Including matrix correction factor 1.0530

 

Table. Measured Concentrations t = 120 h (repeated experiment).

Sample Name

Peak Area
[mAU *min]

Concentration
[mg/L]

Dilution
Factor

Mean
Concentration
[mg/L]

Blank pH 7
t = 120 h

n.a.

< LOQ

None

< LOQ

n.a.

< LOQ

None

pH 7
t=120 h1

5.7610

500.99

50

526.681

5.7675

501.56

50

5.7462

499.70

50

5.8156

505.77

50

5.7047

496.06

50

5.7149

496.96

50

1Including matrix correction factor 1.0530

 

Assessment

The measured change in concentration at each pH value is summarised in Table below.

Table. Measured Concentrations Tier 1.

Mean Concentrations [mg/L]

pH 4

pH 7*

pH 9

pH 7, repeated

Average temperature [°C]

49.2

49.2

49.2

49.3

t = 0 h

488.53

607.29

486.56

524.62

t = 120 h

506.05

531.32

499.90

526.68

Recovery after 120 h [%]

103.6

87.5

102.7

99.6

Change over 120h[%]

+ 3.6

- 12.5

+ 2.7

+ 0.4

* The starting concentration was implausible (too high), therefore the test at pH 7 was repeated

Validity criteria fulfilled:
yes
Conclusions:
Sodium 3-sulfobenzoate is hydrolytically stable after five days (120 hours) at pH values of 4, 7 and 9 and 50°C.
Executive summary:

The determination of pH-dependent Hydrolysis in Water of sodium 3-sulfobenzoate has been performed according to OECD Guideline 111 and EU Method C.7.

Tier 1

A test item solution in demineralised water was mixed with buffer solutions (pH values: 4; 7; and 9). The resulting solutions were sterile filtered and incubated at 50 °C for a period of five days. Samples were analysed at the beginning and after five days. The analysis of the samples (performed with HPLC) showed no decrease > 10 % in the test item concentration within five days.

 

pH

% of start concentration after 5 days

% change within 5 days

4

103.6

+ 3.6

7*

87.5

- 12.5

9

102.7

+ 2.7

7, repeated

99.6

- 0.4

* The starting concentration was implausible (too high), therefore the test at pH 7 was repeated

 

The test item was considered hydrolytically stable at the tested pH values.

Description of key information

The determination of pH-dependent Hydrolysis in Water of sodium 3-sulfobenzoate has been performed according to OECD Guideline 111 and EU Method C.7.

Tier 1

A test item solution in demineralised water was mixed with buffer solutions (pH values: 4; 7; and 9). The resulting solutions were sterile filtered and incubated at 50 °C for a period of five days. Samples were analysed at the beginning and after five days. The analysis of the samples (performed with HPLC) showed no decrease > 10 % in the test item concentration within five days.

pH

% of start concentration after 5 days

% change within 5 days

4

103.6

+ 3.6

7*

87.5

- 12.5

9

102.7

+ 2.7

7, repeated

99.6

- 0.4

* The starting concentration was implausible (too high), therefore the test at pH 7 was repeated

 

The test item was considered hydrolytically stable at the tested pH values.

Key value for chemical safety assessment

Additional information

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