4-hydroxybenzophenone

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

13 November 2018 to 14 November 2019

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:

March 04, 2016

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

Version / remarks:

April 13, 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:

October 2008
EPA Fate, Transport and Transformation Test Guideline

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Appearance: White powder
Purity/Composition: 99.72%
Test item storage: At room temperature desiccated

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

Samples to check concentration and pH were taken at 0 hours, 2.4 hours and 5 days.

Buffers:

Acetate buffer pH 4, 0.1 M: Solution of 16.7% 0.1 M sodium acetate in water and 83.3% 0.1 M acetic acid in water. Buffer contained 0.0009% (w/v) sodium azide.

Phosphate buffer pH 7, 0.1 M: Solution of 0.1 M potassium di-hydrogen-phosphate in water adjusted to pH 7 using 10N sodium hydroxide. Buffer contained 0.0009% (w/v) sodium azide.

Borate buffer pH 9, 0.1 M: Solution of 0.1 M boric acid in water and 0.1 M potassium chloride in water adjusted to pH 9 using 10N sodium hydroxide. Buffer contained 0.0009% (w/v) sodium azide.

The buffer solutions were 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.

Details on test conditions:

Preliminary Test - Tier 1

The test item was spiked to the solutions at a target concentration of 2 mg/L using a spiking solution in acetonitrile. 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 item in the test samples was determined immediately after preparation (t = 0) and after 2.4 hours and 5 days. The samples taken at t = 2.4 hours and t = 5 days were cooled to room temperature using running tap water.

Analysis was performed on subsamples of 750 µL. The samples and blank buffer solutions were diluted in a 3:1 (v:v) ratio with acetonitrile and analyzed.

Blank buffer solutions containing a similar content of blank spiking solution were treated similarly as the test samples and analyzed 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.:

50 °C

Initial conc. measured:

2.07 mg/L

Remarks:

Mean initial concentration

Duration:

5 d

pH:

7

Temp.:

50 °C

Initial conc. measured:

2.02 mg/L

Remarks:

Mean initial concentration

Duration:

5 d

pH:

9

Temp.:

50 °C

Initial conc. measured:

2.04 mg/L

Remarks:

Mean initial concentration

Number of replicates:

2

Statistical methods:

See formulas in 'any other information' section

Preliminary study:

Preliminary Test - Tier 1
The analytical results of the preliminary test are given in Table 10 and Table 11.

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 item at 25°C is > 1 year. According to the guideline, no further tests were required.

No test item was detected in the blank buffer solutions.

The mean recoveries of the of the test item containing buffer solutions at t=0 fell within the criterion range of 90-110%. It demonstrated that the analytical method was adequate to support the hydrolysis study on the test item.

Transformation products:

not measured

% Recovery:

> 100

pH:

4

Temp.:

50 °C

Duration:

5 d

% Recovery:

> 100

pH:

7

Temp.:

50 °C

Duration:

5 d

% Recovery:

> 100

pH:

9

Temp.:

50 °C

Duration:

5 d

Key result

pH:

4

Temp.:

25 °C

DT50:

> 1 yr

Remarks on result:

hydrolytically stable based on preliminary test

Key result

pH:

7

Temp.:

25 °C

DT50:

> 1 yr

Remarks on result:

hydrolytically stable based on preliminary test

Key result

pH:

9

Temp.:

25 °C

DT50:

> 1 yr

Remarks on result:

hydrolytically stable based on preliminary test

Table 10       

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

pH code	Sampling time	Analyzed concentration [mg/L]	Degree of hydrolysis [%]		pH
			Individual	Mean
pH 4	0 hours	2.09			3.9
		2.04			4
	2.4 hours	2.03	1.8	2.1	4
		2.02	2.4		4
	5 days	2.06	0.34	0.64	3.9
		2.05	0.94		4
pH 7	0 hours	2.01			7
		2.02			7
	2.4 hours	2	0.75	0.83	7
		2	0.9		7
	5 days	2.02	-0.072	-0.78	7
		2.05	-1.5		7
pH 9	0 hours	2.03			8.9
		2.04			9
	2.4 hours	2.04	-0.48	-0.25	8.9
		2.04	-0.017		8.9
	5 days	2.12	-4	-4.1	8.9
		2.12	-4.3		8.9

Table 11       

Preliminary Test:  Recoveries

pH code	Nominal concentration [mg/L]	Analyzed concentration [mg/L]	Recovery [%]
			Individual	Mean
pH 4	2	2.09	105	103
	2	2.04	102
pH 7	2	2.01	101	101
	2	2.02	101
pH 9	2	2.03	102	102
	2	2.04	102

Validity criteria fulfilled:

yes

Conclusions:

The preliminary test (Tier 1) performed for the determination of the rate of hydrolysis of 4-Hydroxy-benzophenone at pH values normally found in the environment (pH 4-9). 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.

Executive summary:

In this guideline (OECD 111) study conducted with GLP certification, the test material (EC 214-507-1) was determined to be hydrolytically stable.

Description of key information

Study conducted to recognised testing guidelines with GLP certification.

Key value for chemical safety assessment

Half-life for hydrolysis:

1 yr

at the temperature of:

25 °C

Additional information

Substance is hydrolytically stable at pH 4 to 9.

At pH 4, pH 7 and pH 9, the half-life time of the test item at 25°C is > 1 year.