Orthoperiodic acid

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

06 April 2018 to 28 November 2018

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:

2016

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

Version / remarks:

2004

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.2120 (Hydrolysis of Parent and Degradates as a Function of pH at 25°C)

Version / remarks:

2008

Deviations:

no

GLP compliance:

yes

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

For each sampling time, duplicate sterile vessels under vacuum were filled with 6 mL test solution and placed in the dark in a temperature controlled environment at 50.0°C ± 0.1°C.

Buffers:

BUFFER SOLUTIONS
Acetate buffer pH 4, 0.01 M: Solution of 16.7 % 0.01 M sodium acetate in water and 83.3 % 0.01 M acetic acid in water. Buffer contained 0.0009 % (w/v) sodium azide.

Phosphate buffer pH 7, 0.01 M: Solution of 0.01 M potassium di-hydrogen-phosphate in water adjusted to pH 7 using 1N sodium hydroxide. Buffer contained 0.0009 % (w/v) sodium azide.

Borate buffer pH 9, 0.01 M: Solution of 0.01 M boric acid in water and 0.01 M potassium chloride in water adjusted to pH 9 using 1 N sodium hydroxide. Buffer contained 0.0009 % (w/v) sodium azide.

Hydrochloride acid/potassium chloride buffer pH 1.3, 0.1 M: Approximately 3.728 gram of potassium chloride and 5.6 mL of hydrochloric acid was added to 1 000 mL of water.

Details on test conditions:

PRELIMINARY TEST - TIER 1
- The test material was spiked to the buffer solutions at a target concentration of 40 mg/L using a spiking solution in water. Each solution was filter-sterilised through a 0.2 µm FP 30/0.2 CA-S filter (Whatman, Dassel, Germany) and transferred into a sterile vessel. To exclude oxygen, nitrogen gas was purged through the solution for 5 minutes. For each sampling time, duplicate sterile vessels under vacuum were filled with 6 mL test solution and placed in the dark in a temperature controlled environment at 50.0 °C ± 0.1 °C.
- The spiking volume was ≤ 1 % of the sample volume. Nominal concentrations were not corrected for the spiking volume.
- The concentration of the test material in the test samples was determined immediately after preparation (t=0) and after 5 days. The samples taken at t=5 days were cooled to room temperature using running tap water. Samples were transferred to a glass container and analysed.
- Blank buffer solutions containing a similar content of blank spiking solution were treated similarly as the test samples and analysed at t=0.
- The pH of each of the test solutions (except for the blanks) was determined at each sampling time.

Duration:

5 d

pH:

4

Temp.:

25 °C

Duration:

5 d

pH:

7

Temp.:

25 °C

Duration:

5 d

pH:

9

Temp.:

25 °C

Number of replicates:

Two

Positive controls:

no

Negative controls:

no

Preliminary study:

PRELIMINARY TEST - TIER 1
- At pH 4, pH 7 and pH 9, a degree of hydrolysis of < 10 % was observed after 5 days. It demonstrated that the half-life time of the test material at 25 °C is > 1 year. According to the guideline, no further tests were required.
- No test material was detected in the blank buffer pH 9 samples. A small response at the retention time of the test item was detected in one of the two blank buffer pH 7 samples, which was considered to be an instability of the baseline rather than test material. Small responses at the retention time of the test material were detected in the chromatograms of both blank buffer pH 4 samples. It is not considered to influence the study results since it is caused by a matrix component from the pH 4 buffer and, therefore, corrected for by the matrix matched calibration curve.
- The mean recoveries of the test material containing buffer solutions at t=0 did not fall within the criterion range of 90-110 % for buffer pH 4 and pH 9. This does not impact the study outcome since the deviation from the criterion is small and the degree of hydrolysis is expressed relative to the t=0 hour samples.

Transformation products:

not measured

pH:

4

Temp.:

25 °C

DT50:

> 1 yr

pH:

7

Temp.:

25 °C

DT50:

> 1 yr

pH:

9

Temp.:

25 °C

DT50:

> 1 yr

Preliminary Test: Hydrolysis of the Test Material at pH 4, pH 7 and pH 9

pH code	Sampling time	Analysed concentration [mg/L]	Degree of hydrolysis [%]		pH
			Individual	Mean
pH 4	0 hours	44.9			4.0
		45.1			4.0
	5 days	45.3	-0.60	0.14	4.1
		44.6	0.88		4.1
pH 7	0 hours	44.0			7.0
		44.2			7.0
	5 days	43.8	0.78	0.49	7.0
		44.1	0.21		7.0
pH 9	0 hours	46.2			8.9
		46.3			8.9
	5 days	46.9	-1.4	-1.3	9.0
		46.8	-1.2		9.0

 

Preliminary Test: Recoveries

pH code	Nominal concentration [mg/L]	Analysed concentration [mg/L]	Recovery [%]
			Individual	Mean
pH 4	40.0	44.9	112	113
	40.0	45.1	113
pH 7	40.0	44.0	110	110
	40.0	44.2	111
pH 9	40.0	46.2	116	116
	40.0	46.3	116

 

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of the test a degree of hydrolysis at each pH value of < 10 % was observed after 5 days. The half-life time of the test material at 25 °C is > 1 year. According to the guideline, performance of the main study (Tier 2) was not required.

Executive summary:

The hydrolysis rate of the test material was assessed according to EC Guideline C.7., OECD Guideline 111 and EPA Guideline OPPTS 835.2120 in accordance with the principles of GLP at pH values normally found in the environment (pH 4-9).

The test material was spiked to the buffer solutions at a target concentration of 40 mg/L using a spiking solution in water, filter-sterilised and transferred into a sterile vessel. To exclude oxygen, nitrogen gas was purged through the solution for 5 minutes. For each sampling time, duplicate sterile vessels under vacuum were filled with 6 mL test solution and placed in the dark in a temperature controlled environment at 50.0 °C ± 0.1 °C.

The concentration of the test material in the test samples was determined immediately after preparation (t=0) and after 5 days. The samples taken at t=5 days were cooled to room temperature using running tap water. Samples were transferred to a glass container and analysed using HPLC.

No test material was detected in the blank buffer pH 9 samples. A small response at the retention time of the test material was detected in one of the two blank buffer pH 7 samples, which was considered to be an instability of the baseline rather than test material. Small responses at the retention time of the test material were detected in the chromatograms of both blank buffer pH 4 samples. It is not considered to influence the study results since it is caused by a matrix component from the pH 4 buffer and, therefore, corrected for by the matrix matched calibration curve.

At each pH value a degree of hydrolysis of < 10 % was observed after 5 days. According to the guideline, performance of the main study (Tier 2) was not required.

Under the conditions of the study the half-life time of the test material at 25 °C is > 1 year.

Description of key information

Under the conditions of the test a degree of hydrolysis at each pH value of < 10 % was observed after 5 days. The half-life time of the test material at 25 °C is > 1 year.  According to the guideline, performance of the main study (Tier 2) was not required.

Key value for chemical safety assessment

Half-life for hydrolysis:

1 yr

at the temperature of:

25 °C

Additional information

The hydrolysis rate of the test material was assessed according to EC Guideline C.7., OECD Guideline 111 and EPA Guideline OPPTS 835.2120 in accordance with the principles of GLP at pH values normally found in the environment (pH 4-9). The study was assigned a reliability score of 1 in accordance with the principles for assessing data quality as outlined by Klimisch et al. (1997).

The test material was spiked to the buffer solutions at a target concentration of 40 mg/L using a spiking solution in water, filter-sterilised and transferred into a sterile vessel. To exclude oxygen, nitrogen gas was purged through the solution for 5 minutes. For each sampling time, duplicate sterile vessels under vacuum were filled with 6 mL test solution and placed in the dark in a temperature controlled environment at 50.0 °C ± 0.1 °C.

The concentration of the test material in the test samples was determined immediately after preparation (t=0) and after 5 days. The samples taken at t=5 days were cooled to room temperature using running tap water. Samples were transferred to a glass container and analysed using HPLC.

No test material was detected in the blank buffer pH 9 samples. A small response at the retention time of the test material was detected in one of the two blank buffer pH 7 samples, which was considered to be an instability of the baseline rather than test material. Small responses at the retention time of the test material were detected in the chromatograms of both blank buffer pH 4 samples. It is not considered to influence the study results since it is caused by a matrix component from the pH 4 buffer and, therefore, corrected for by the matrix matched calibration curve.

At each pH value a degree of hydrolysis of < 10 % was observed after 5 days. According to the guideline, performance of the main study (Tier 2) was not required.

Under the conditions of the study the half-life time of the test material at 25 °C is > 1 year.