Aluminum magnesium vanadium oxide

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

03 Dec 2019 - 12 Feb 2020

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:

adopted 13 Apr 2004

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

adopted 31 May 2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

- Sampling intervals for the parent/transformation products: samples were analysed on day 0 and 5
- Sample storage conditions before analysis: Samples were stored for 5 days at 50°C

Buffers:

- pH: 4, 7, 9
- Composition of buffer:
pH 4 (160 mL CH3COOH, 2 M + 80 mL CH3COONa, 1 M + ad. 2000 mL water p.a.)
pH 7 (17.4173 g KH2PO4 + 1000 mL water + 29.8 mL NaOH, 2M + ad. 2000 mL water p.a.)
ph 9 (6.1864 g H3BO3 + 7.4582 g KCL + 1000 mL water p.a. + 21.5 mL NaOH, 2M + ad 2000 mL water p.a.)
During the repetition of the tier 1 in pH 9 buffer, the buffer was prepared as follows: 6.1860 g H3BO3 + 7.4582 g KCL + 1000 mL water p.a. + 21.5 mL NaOH, 2M + ad 2000 mL water p.a.

Details on test conditions:

TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: 60 mL PP flasks
- Sterilisation method: solutions were membrane filtrated via sterile 0.45 µm nylon filters andadditionally filtrated via 0.2 µm nylon filters
- Lighting: no
TEST MEDIUM
- Volume used/treatment: 5 g test item with 100 mL water p.a.
- Preparation of test medium: The dissolution of aluminium magnesium vanadium oxide was done similar to OECD 105 enhanced method for synthetic amorphous silica SAS. The saturated test item solutions were further diluted in order to achieve the condition < 0.01 M as laid down in OECD 111. Due to higher solubility of the test item in pH 4 and 7 buffer solutions, the pH 4 solutions were 10 fold diluted, pH 7 solution 4f old and pH 9 solutions 2 fold diluted in order to achieve the concentration < 0.01 M or half saturated concentration. The test item solutions with the concentration 50 g/L were separately prepared in pH 4, 7 and 9 buffer solutions and were shaken for 70.5 h at room temperature.
OTHER TEST CONDITIONS
- Adjustment of pH: yes

Duration:

5 d

pH:

4

Temp.:

50 °C

Initial conc. measured:

50 g/L

Remarks:

10 fold diluted

Duration:

5 d

pH:

7

Temp.:

50 °C

Initial conc. measured:

50 g/L

Remarks:

4 fold diluted

Duration:

5 d

pH:

9

Temp.:

50 °C

Initial conc. measured:

50 g/L

Remarks:

2 fold diluted

Number of replicates:

2

Positive controls:

no

Negative controls:

no

Statistical methods:

Concentrations were determined using linear calibration function. Stability in % at time t was calculated dividing the concentration of Al/Mg/V after 5 d storage by the concentration of AI/MG/V at the beginning of tier 1.

Transformation products:

no

pH:

4

Temp.:

50 °C

DT50:

> 1 yr

pH:

7

Temp.:

50 °C

DT50:

> 1 yr

pH:

9

Temp.:

50 °C

DT50:

> 1 yr

Details on results:

TEST CONDITIONS
- pH, sterility, temperature, and other experimental conditions maintained throughout the study: Yes

Summary Al

pH nominal	Dilution factor	0 h		5 d		Stability [%]
		Conc. Al [mg/L]	RSD [%]	Conc. Al [mg/L]	RSD [%]
pH 4	10	< 0.05	-	< 0.05	-	-
pH 7	4	1.743	3.2	1.853	2.1	106.3
pH 9	2	50.57	3.4	41.06	4.9	81.2

 

Summary Mg

pH nominal	Dilution factor	0 h		5 d		Stability [%]
		Conc. Mg [mg/L]	RSD [%]	Conc. Mg [mg/L]	RSD [%]
pH 4	10	123.8	1.2	122.1	1.2	98.6
pH 7	4	< 2.0	-	< 2.0	-	-
pH 9	2	< 2.0	-	< 2.0	-	-

 

Summary V

pH nominal	Dilution factor	0 h		5 d		Stability [%]
		Conc. Mg [mg/L]	RSD [%]	Conc. Mg [mg/L]	RSD [%]
pH 4	10	< 0.03	-	< 0.03	-	-
pH 7	4	65.12	0.3	65.97	3.3	101.3
pH 9	2	0.601	2.7	0.616	0.8	102.5

 

Description of key information

The amounts of Al (pH 7) / Mg / V after five days was more than 90% of the amount at the start of the test, therefore Aluminium magnesium vanadium was considered to be stable.

Additional information

The hydrolysis and stability of the dissolved test item Aluminium magnesium vanadium oxide in dependence of the pH was determined by measurement of Aluminium (Al), Magnesium (Mg) and Vanadium (V) concentrations in filtrated test solutions with the nominal concentration 50 g/L (10 fold diluted pH 4 buffer solution, 4 fold diluted pH 7 buffer solution and 2 fold diluted pH 9 buffer solutions). As more than 90% of Mg and V was found after

the storage of solutions for 5 days at 50 °C, the whole test item was considered to be stable, and no further examination was made.