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Hydrolysis

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Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
02 August 2018 to 09 August 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EPA OPPTS 835.2130 (Hydrolysis as a Function of pH and Temperature)
Deviations:
no
GLP compliance:
yes
Specific details on test material used for the study:
Reference Identification: Sodium 2,4,5-trichlorobenzenesulphonate
CAS#: 53423-65-7
EC# 258-548-3
Common Name: STB-FR
Product Sample: Sodium Trichlorobenzene Sulfonate; (STB-FR) Lot: 1804-11 Approx. 300g
Date and Quantity Received: 05 Jun 18; 314.3 g (GW)
Physical Description: Solid white powder
Storage Conditions: Room temperature
Radiolabelling:
no
Analytical monitoring:
yes
Details on sampling:
Measurements of the test item in the buffered solutions were at the beginning of the experiment on Day 1 and at the end of the experiment on Day 5.
Buffers:
Stock Solutions for Buffer Preparations:
To make the stock solutions for pH 4 buffer, 0.286 mL of glacial acetic acid and 0.4102 g of sodium acetate was brought to 50 mL volume in separate flasks with HPLC water. To make the stock solution for the pH 7 buffer, 0.6800 g of potassium phosphate was brought to 50 mL with HPLC water. To make the stock solutions for the pH 9 buffer, 0.3091 g of boric acid and 0.3728 g potassium chloride were placed together and brought to 50 mL volume with HPLC water.

Buffer Preparations:
The pH 4.0 buffer solution was prepared by mixing 18 mL of the sodium acetate solution with 82 mL of acetic acid solution. The pH 7.0 buffer solution was prepared by mixing 29.63 mL of sodium hydroxide with 50 mL of potassium phosphate solution and bringing it to 100 mL with HPLC water. The pH 9.0 buffer solution was prepared by mixing 21.3 mL of sodium hydroxide and 50 mL of boric acid and bringing it to 100 mL with HPLC water.

Buffers were sterilized by autoclave immediately after preparation and the pH verified against standardization solutions. The pH was determined using a Fisher Scientific Accumet AB15 pH meter using an ATC Epoxy Body Liquid-filled Combination Electrode with Ag/AgCl Reference for all pH measurements pursuant to the study.
Details on test conditions:
Sample aliquots were added to three buffer solutions and analyzed by high performance liquid chromatography to determine concentration of the solution at pH 4, pH 7 and pH 9 for a baseline analysis. Samples were then stored at 50°C for five days and the analysis was repeated on Day 5.
Duration:
5 d
pH:
3.9
Temp.:
50 °C
Initial conc. measured:
3 135.16 mg/L
Duration:
5 d
pH:
7.06
Temp.:
50 °C
Initial conc. measured:
3 089.92 mg/L
Duration:
5 d
pH:
8.98
Temp.:
50 °C
Initial conc. measured:
3 063.45 mg/L
Number of replicates:
3
Positive controls:
no
Negative controls:
no
Preliminary study:
There was less than 10% degradation at pH 4, pH 7, and pH 9 after 5 days.
Transformation products:
not measured
Details on hydrolysis and appearance of transformation product(s):
The substance did not hydrolyze at pH 4, pH 7, or pH 9 after 5 days.
% Recovery:
99.07
St. dev.:
3.84
pH:
4
Temp.:
50 °C
Duration:
5 d
Remarks on result:
hydrolytically stable based on preliminary test
% Recovery:
99.02
St. dev.:
3.84
pH:
7
Temp.:
50 °C
Duration:
5 d
Remarks on result:
hydrolytically stable based on preliminary test
% Recovery:
96.63
St. dev.:
3.84
pH:
9
Temp.:
50 °C
Duration:
5 d
Remarks on result:
hydrolytically stable based on preliminary test
Key result
pH:
4
Temp.:
50 °C
Hydrolysis rate constant:
0 h-1
DT50:
8 909 h
Type:
(pseudo-)first order (= half-life)
Remarks on result:
hydrolytically stable based on preliminary test
Key result
pH:
7
Temp.:
50 °C
Hydrolysis rate constant:
0 h-1
DT50:
8 460 h
Type:
(pseudo-)first order (= half-life)
Remarks on result:
hydrolytically stable based on preliminary test
Key result
pH:
9
Temp.:
50 °C
Hydrolysis rate constant:
0 h-1
DT50:
2 425 h
Type:
(pseudo-)first order (= half-life)
Remarks on result:
hydrolytically stable based on preliminary test

Variance from Day 0 to Day 5

pH

Day0 (mg/L)

Day5 (mg/L)

Change (mg/L)

Variance (%)

pH4

3135.16

3106.02

-29.14

-0.93

pH7

3089.92

3059.69

-30.23

-0.98

pH9

3063.45

2960.17

-103.28

-3.37

Validity criteria fulfilled:
yes
Conclusions:
The test substance does not hydrolyze at pH 4, pH 7, or pH 9 at 50 deg C after 5 days.
Executive summary:

In a GLP OECD 111 guideline study to assess hydrolysis as a function of pH, the test substance did not degrade by more than 10% after 5 days at pH 4, pH 7, or pH 9 and 50 deg C and can therefore be regarded as hydrolytically stable and no further testing is needed. Estimated half-lives were 2425 hours at pH 9, 8460 hours at pH 7, and 8909 hours at pH 4.

Description of key information

In a GLP OECD 111 guideline study to assess hydrolysis as a function of pH, the test substance did not degrade by more than 10% after 5 days at pH 4, pH 7, or pH 9 and 50 deg C and can therefore be regarded as hydrolytically stable and no further testing is needed. Estimated half-lives were 2425 hours at pH 9, 8460 hours at pH 7, and 8909 hours at pH 4.

Key value for chemical safety assessment

Half-life for hydrolysis:
2 425 h
at the temperature of:
50 °C

Additional information

Estimated half-lives were 2425 hours at pH 9, 8460 hours at pH 7, and 8909 hours at pH 4.