Phosphoric acid, 2-ethylhexyl ester, sodium salt

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

from 2019-07-30 to 2019-09-04

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:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

The test solutions were analysed at the start of the test and after five days with five replicate samples each. Two replicate tubes filled with control buffers were analysed at the start and at the end of the incubation. Aqueous and control samples were hundredfold diluted with the mobile phase and analysed by LC/MS/MS method.

Buffers:

- pH 4.0: 1 mL 0.2 M Sodium hydroxide and 125 mL 0.2 M Potassium hydrogen phthalate were diluted to 500 mL with Ultrapure water.
- pH 7.0: 74 mL 0.2 M Sodium hydroxide and 125 mL 0.2 M Potassium dihydrogen phosphate were diluted to 500 mL with Ultrapure water.
- pH 9.0: 53.5 mL 0.2 M Sodium hydroxide and 125 mL 0.2 M Boric acid and Potassium chloride were diluted to 500 mL with Ultrapure water.

These sterile buffer solutions were prepared using reagent grade chemicals and ultrapure, sterile water. The pH of each buffer solution was checked with a calibrated pH meter to a precision of at least 0.01.

Details on test conditions:

TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: glass headspace-vials
- Lighting: darkness
- Measures taken to avoid photolytic effects: complete darkness

TEST MEDIUM
- Volume used/treatment: 20 mL of the test item solution in each buffer
- Kind and purity of water: ultrapure water

OTHER TEST CONDITIONS
- Adjustment of pH: none
- Temperature: 50 ± 0.5 °C

Duration:

5 d

pH:

4

Temp.:

50 °C

Initial conc. measured:

>= 1 004 - <= 1 087 mg/L

Duration:

5 d

pH:

7

Temp.:

50 °C

Initial conc. measured:

>= 999 - <= 1 030 mg/L

Duration:

5 d

pH:

9

Temp.:

50 °C

Initial conc. measured:

>= 876 - <= 897 mg/L

Number of replicates:

5 tubes per test solution
2 tubes for the control

Positive controls:

no

Negative controls:

yes

Preliminary study:

In the course of the preliminary test the test item proved to be hydrolytically stable at pH 4, 7 and 9. The recovery of the test item after 5 days incubation period was 92 - 110 %.

Transformation products:

not measured

% Recovery:

92

pH:

4

Temp.:

50 °C

Duration:

5 d

Remarks on result:

hydrolytically stable based on preliminary test

% Recovery:

102

pH:

7

Temp.:

50 °C

Duration:

5 d

Remarks on result:

hydrolytically stable based on preliminary test

% Recovery:

110

pH:

9

Temp.:

50 °C

Duration:

5 d

Remarks on result:

hydrolytically stable based on preliminary test

Key result

Remarks on result:

hydrolytically stable based on preliminary test

Measured data

pH	Sampling time, day	Concentration of the test item				Measured pH
		Results of the replicates, mg/L	Mean, mg/L	Measured/ Nominal, %	End/Start, %
4	0 (Start)	Control buffers		-	-	4.01
		1020	1036	102	-	4.17
		1054
		1087
		1004
		1017
	5	Control buffers		-	-	4.16
		979	947	93	92	4.18
		964
		889
		961
		944
7	0 (Start)	Control buffers		-	-	7.02
		1018	1017	101	-	6.91
		1016
		1023
		1030
		999
	5	Control buffers		-	-	6.94
		1042	1038	103	102	6.92
		1008
		1061
		1035
		1045
9	0 (Start)	Control buffers		-	-	9.00
		876	886	88	-	8.94
		897
		886
		889
		882
	5	Control buffers		-	-	9.00
		971	974	97	110	8.96
		959
		960
		1009
		974

Validity criteria fulfilled:

yes

Conclusions:

Hydrolysis preliminary test was carried out with the test item at 50 ± 0.5 °C at three different pH values. After five days the test item proved to be hydrolytically stable.

Executive summary:

The hydrolysis of the test item was assessed in accordance with the OECD guideline 111 and the EU method C.7 in a preliminary test. The hydrolysis of the test item in different aqueous buffer solutions (pH = 4, 7 and 9) at 50 °C was investigated. The test solutions were analysed at the start of the test and after five days with five replicate samples each. Two replicate tubes filled with control buffers were analysed at the start and at the end of the incubation. Aqueous and control samples were hundredfold diluted with the mobile phase and analysed by LC-MS/MS method. The recovery of the test item after 5 days at each pH value was in the range of 92 – 110 %. In the course of the preliminary test the test item proved to be hydrolytically stable at pH 4, 7 and 9. Thus, a main test was not required.

Description of key information

Hydrolysis preliminary test was carried out with the test item at 50 ± 0.5 °C at three different pH values. After five days the test item proved to be hydrolytically stable.

Additional information

The hydrolysis of the test item was assessed in accordance with the OECD guideline 111 and the EU method C.7 in a preliminary test. The hydrolysis of the test item in different aqueous buffer solutions (pH = 4, 7 and 9) at 50 °C was investigated. The test solutions were analysed at the start of the test and after five days with five replicate samples each. Two replicate tubes filled with control buffers were analysed at the start and at the end of the incubation. Aqueous and control samples were hundredfold diluted with the mobile phase and analysed by LC-MS/MS method. The recovery of the test item after 5 days at each pH value was in the range of 92 – 110 %. In the course of the preliminary test the test item proved to be hydrolytically stable at pH 4, 7 and 9. Thus, a main test was not required.