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Hydrolysis

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Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From 2018-03-26 to 2018-04-20
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
GLP compliance:
yes
Specific details on test material used for the study:
Lot No.: 20170707
Purity: 99.13%
Analytical monitoring:
yes
Details on sampling:
Test solutions were prepared in pH 4, 7, and 9 buffers at approximately 21.19 µg/mL by adding 100.0 µL of the dosing solution into 100-mL volumetric flasks, and bringing to volume with the respective buffers. All flasks were mixed by inversion.
Each dosed solution was distributed into individual 4-dram vials for the Day 0 samples and three, 4-dram vials for the Day 5 samples, which were filled leaving noheadspace. The samples designated for sampling on Day 5 were placed in an oven set to 50°C. The pH of each Day 0 sample was measured. Buffers containingno test material were analyzed to check for background contamination or buffer interference.
After five days of incubation at 50°C, the Day 5 samples were removed from incubation and prepared for analysis as previously described. The pH of representative samples was measured after the Day 5 sampling.
Day 0 and Day 5 Quality Control (QC) samples were prepared in methanol at 21.19 µg/mL by adding 100.0 µL of the dosing solution into a 100-mL volumetric flask, and bringing the flask to volume with methanol.
Buffers:
pH 4 Buffer: Each liter of 0.05 M pH 4 buffer solution was prepared by adding 4 mL of 0.1 M NaOH (aq) and 500 mL of 0.1 M potassium hydrogen phthalate (aq) to a total volume of 1 L with reagent water. A 0.01 M pH 4 buffer solution was prepared by adding 200 mL of the 0.05 M pH 4 buffer to 800 mL of reagent water. The final pH of the solution was 4.015.

pH 7 Buffer: Each liter of 0.05 M pH 7 buffer solution was prepared by adding 296 mL of 0.1 M NaOH (aq) and 500 mL of 0.1 M KH2PO4 (aq) to a total volume of 1 L with reagent water. A 0.01 M pH 7 buffer solution was prepared by adding 200 mL of the 0.05 M pH 7 buffer to 800 mL of reagent water. The final pH of the solution was 7.016.

pH 9 Buffer: Each liter of 0.05 M pH 9 buffer solution was prepared by adding 213 mL of 0.1 M NaOH (aq) and 500 mL of 0.1 M H3BO3 (aq) in 0.1 M KCl to a total volume of 1 L with reagent water. A 0.01 M pH 9 buffer solution was prepared by adding 200 mL of the 0.05 M pH 9 buffer to 800 mL of reagent water. The finalpH of the solution was 9.011.

All buffer solutions used for testing were sterilized prior to use by filtering through a 0.45-µm or smaller filter, and were autoclaved (~121°C at 15 psi for ~30 minutes). The buffer solutions were stored at room temperature.
Details on test conditions:
Preparation of Test and Reference Substance Solutions:
A 1.486-mg/mL stock solution of the test substance was prepared by weighing 14.99 mg of the test substance into a 10-mL volumetric flask, correcting for purity (99.13%), and bringing the flask to volume with methanol. Subsequent dilutions were prepared in methanol and were used as analytical standards.
A 21.19-mg/mL stock solution of the test substance was prepared by weighing 106.87 mg of the test substance into a 5-mL volumetric flask, correcting for purity (99.13%), and bringing the flask to volume with methanol. This stock solution was used as the dosing solution. A subsequent dilution was prepared in methanol and used as an analytical QC check standard.
All solutions were properly labeled and refrigerated when not in use.
Duration:
5 d
pH:
4
Temp.:
50 °C
Initial conc. measured:
21.12 other: µg/mL
Duration:
5 d
pH:
7
Temp.:
50 °C
Initial conc. measured:
21.21 other: µg/mL
Duration:
5 d
pH:
9
Temp.:
50 °C
Initial conc. measured:
21.2 other: µg/mL
Number of replicates:
2
Statistical methods:
Calculations, including averages, standard deviations, and linear regression, were performed using Microsoft Excel (version 2016). Values in the Excel spreadsheets were not rounded during the calculations (i.e. calculations performed using Excel in full precision mode). Consequently, values represented in the raw data and report may be slightly different when calculated by hand.
Preliminary study:
The results indicate that test item was hydrolytically stable (<10% degradation) at pH 4, 7, and 9 when stored at 50°C for five days.
Transformation products:
no
% Recovery:
99.2
Duration:
5 d
Key result
pH:
4
Temp.:
50 °C
DT50:
329.2 d
Key result
pH:
7
Temp.:
50 °C
DT50:
1 425 d
Key result
pH:
9
Temp.:
50 °C
DT50:
519.1 d
 pH condition  Mean Day 0 test item Concentration  (µg/mL)  Mean Day 5 test item Concentration  (µg/mL)  (% of initial)  Test item DT50 (days)
pH 4  21.12  20.90 (98.9)  329.2 
pH 7  21.21  21.16 (99.8) 1,425 
 pH 9  21.20  21.06 (99.3)  519.1
Validity criteria fulfilled:
yes
Conclusions:
The test item was determined to be hydrolytically stable (<10% degradation) in sterile aqueous solutions buffered at pH 4, 7, and 9 after incubation for five days at 50 ± 0.5°C.
Executive summary:

The purpose of this study was to determine the hydrolytic stability of the test at 50°C in pH 4, 7, and 9 sterile aqueous buffer solutions. The study was conducted with OECD Guideline 111 and U.S. EPA OPPTS 835.2120, Hydrolysis.

This report describes the determination of the stability of the test substance in aqueous buffer solutions. Samples were analyzed using a high-performance liquid chromatography system with ultraviolet detection (HPLC- UV).

The test item was determined to be hydrolytically stable (<10% degradation) in sterile aqueous solutions buffered at pH 4, 7, and 9 after incubation for five days at 50 ± 0.5°C.

The half-life (DT50) were 329.2, 1425 and 519.1 days at pH 4, 7 and 9 respectively.

Description of key information

The test item was determined to be hydrolytically stable (<10% degradation) in sterile aqueous solutions buffered at pH 4, 7, and 9 after incubation for five days at 50 ± 0.5°C. The half-life (DT50) were 329.2, 1425 and 519.1 days at pH 4, 7 and 9 respectively.

Key value for chemical safety assessment

Half-life for hydrolysis:
1 425 d
at the temperature of:
50 °C

Additional information

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