Benzene, 1,1'-oxybis[methyl-, sulfonated, ammonium salts

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

6 October 2017 - 16 February 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)

Version / remarks:

2004

Deviations:

yes

Remarks:

see field principles of method if other than guideline

Qualifier:

according to guideline

Guideline:

EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)

Version / remarks:

(EC) No 440/2008

Deviations:

yes

Remarks:

see field principles of method if other than guideline

Principles of method if other than guideline:

Deviations:
The temperature could not be held at the required 50 ± 0.5 °C. The temperature ranged from 44.6 to 54.8 °C with a mean of 50.0 °C. Considering that no hydrolysis was observed for all pH levels and that the mean temperature was in the given range, this variation seems not to have had a considerable effect on the outcome of this study.

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Batch No: INB3209089
Storage: At room temperature, protected from light

Analytical monitoring:

yes

Details on sampling:

- Sampling method:
Sampling for each series of HPLC analysis were performed under sterile conditions (Bunsen burner, fume hood) as follows:
- Vessels were taken out of the thermostat cabinet
- Sampling: 5 ml were transferred with a sterilized pipette tip into a test tube (samples for HPLC do not need to be sterile, but the test vessels must remain sterile). Samples were not filtered.
- Replacing the nitrogen in the headspace of the test vessel and immediate closure with screw cap; vessels are brought back to the thermostat cabinet and put on the stirring device.
- Measurement of pH (precision 0.1 unit) with the remaining sample volume.


- Sampling intervals:
about 5 min past test start to ensure complete dissolution of the test item and at regular intervals daily from day 1 to 5.

- Sample storage conditions before analysis:
Immediate HPLC measurement or freezing of the sample after sample preparation

Buffers:

pH 4:
mixture of 0.05 M sodium acetate and 0.05 M acetic acid
19 ml 0.05 M sodium acetate and 81 ml 0.05 M acetic acid

pH 7:
mixture of 0.1 M monopotassium phosphate and 0.1 N NaOH
29.63 ml 0.1 N NaOH + 50 ml 0.1 M monopotassium phosphate to 100 ml (means “Milli-Q water ad 100 ml") as described in the OECD guideline 111 for a temperature of 20 °C

pH 9:
mixture of 0.1 M H3BO3 in 0.1 M KCl and 0.1 N NaOH
21.3 ml 0.1 N NaOH + 50 ml 0.1 M H3BO3 to 100 ml with 0.1 M KCl as described in the OECD guideline 111 for a temperature of 20 °C

Details on test conditions:

Study design
Two test vessels (buffer with test item), as well as a blank vessel (buffer without test item) were prepared for each pH value (4, 7, 9), yielding six test vessels and three blank vessels in total. Potential hydrolysis of the test item was followed by HPLC analysis over five days. Each replicate was sampled every day during the test.

Test system and test conditions
A concentration of about 200 mg/l test item was incubated for 5 days at ca. 50 °C (in thermostat cabinet) in three different buffers at pH 4, 7 and 9 in 100 ml vessels (Schott, Duran).

Preparation of the test
The test and blank vessels (including a magnetic rod for stirring) as well as the pipette tips used for sampling were sterilized by autoclaving before use. Preparation of the buffers was done in separate, large glass vessels. The respective buffers including the headspace were sparged with nitrogen for about thirty minutes to minimize reaction of the test item with oxygen. Then, the vessel was closed, and placed at the respective temperature for at least three hours to allow for temperature equilibration. Subsequently, the pH of the buffers was checked and corrected, before three times 100 ml of each buffer solution was filter-sterilized (0.45 µm aPES membrane, Rapid-Flow, Thermo Scientific) directly into the test and blank vessels.

The test item was added from an aqueous stock solution of about 20 g/l to stirred buffer solutions. The same amount of ultra-pure water without the test item was added to the blank vessels. Then the headspace of each test and blank vessel was filled with nitrogen, the vessels were closed, brought back into the thermostat cabinet, and stirred. The pH of the test solutions was not adjusted after addition of the test item, as no significant changes were expected due to the high buffer capacity.
The test item solutions were stirred in the thermostat cabinet for about five minutes to ensure complete dissolution of the test item before the first sampling (t0) for HPLC measurement was performed.
Hydrolysis of the test item was then followed over five days, with one HPLC sampling per day (t1 – t5), at intervals of about 24 h. The time of sampling was recorded.

Positive controls:

no

Negative controls:

no

Preliminary study:

The nominal start concentration was 200 mg/l test item. The analytically determined, mean start concentrations were 166 mg/l, 189 mg/l and 181 mg/l at pH 4,7 and 9, respectively, corresponding to recovery rates of about 83%, 95% and 91%. This is considered to be an acceptable range, as the test item is a complex mixture resulting in a very broad HPLC peak, whose integration is much more prone to variance in comparison with a sharp test item peak from a single substance test item.

At pH 4, 7 and 9, the observed decrease of the mean test item concentrations was no higher than 6.5% over the duration of the test and thus not significant according to TG OECD 111, as the observed decrease was below 10% over a duration of five days. This can also be seen in Figure 1 (see illustration), which demonstrates the analytical variance of the data obtained with no clear trends as to a concentration decrease due to hydrolysis. Furthermore, the peak shape of the substance mixture, which constitutes the test item, remained the same from start to end of the test and all pH levels.

Transformation products:

no

Key result

pH:

4

Temp.:

50 °C

Remarks on result:

hydrolytically stable based on preliminary test

Key result

pH:

7

Temp.:

50 °C

Remarks on result:

hydrolytically stable based on preliminary test

Key result

pH:

9

Temp.:

50 °C

Remarks on result:

hydrolytically stable based on preliminary test

Validity criteria fulfilled:

yes

Remarks:

No validity criteria are given by TG OECD 111. The requirements which were not fulfilled are mentioned in the field "Overall remarks".

Conclusions:

The hydrolysis of the test item Benzene, 1,1’-oxybis(methyl-, sulfonated, ammonium salt (ca 50% ) (CAS no. of main component 75314-26-0) was investigated in a tier 1 study according to guideline OECD 111.
Based on the results, the test item was considered to be hydrolytically stable in the environmentally relevant range of pH 4 to 9.

Executive summary:

The hydrolysis of the test item Benzene, 1,1’-oxybis(methyl-, sulfonated, ammonium salt (ca 50% ) (CAS no. of main component 75314-26-0) was investigated in a Tier 1 test according to TG OECD 111.

The hydrolysis of the test item was investigated by incubating solutions of about 200 mg test item/l at three environmentally relevant pH values (pH 4, 7 and 9) and about 50 °C over five days.

At pH 4, 7 and 9, the observed decrease of the mean test item concentrations was no higher than 6.5% over the duration of the test and thus not significant according to TG OECD 111. Additionally, the peak shape of the substance mixture, which constitutes the test item, remained the same from start to end of the test and all pH levels.

Consequently, the test item Benzene, 1,1’-oxybis(methyl-, sulfonated, ammonium salt (ca 50% ) (CAS no. of main component 75314-26-0) was considered to be hydrolytically stable in the environmentally relevant range of pH 4 to 9.

Description of key information

The hydrolysis of the test item Benzene, 1,1’-oxybis(methyl-, sulfonated, ammonium salt (ca 50% ) (CAS no. of main component 75314-26-0) was investigated in a tier 1 study according to guideline OECD 111.

Based on the results, the test item was considered to be hydrolytically stable in the environmentally relevant range of pH 4 to 9.

Additional information

Based on the results of a tier 1 study according to guideline OECD 111, the test item was considered to be hydrolytically stable in the environmentally relevant range of pH 4 to 9.