4,4'-dioxo-4,4'-dioxydibutyric acid

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

from 2017-11-24 to 2018-03-15

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

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:

no

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

The concentration of the test substance could not be determined with enough accuracy to calculate the rate of hydrolysis. Therefore the increasing concentration of the hydrolysis product, succinic acid, was measured to give an indication on the rate of hydrolysis. The concentration was measured at the beginning of the test and after 3, 4, 6, 8, 24, 31 and 48 hours.

Buffers:

Sterilised buffer solutions at pH 4, 7 and 9 were prepared according to Annex 3 of OECD TG 111.

Details on test conditions:

Spiked buffer solutions were prepared by weighing the test substance into separate volumetric flasks, which were brought to volume with sterilised buffer solutions, pH 4, 7 and 9. The spiked buffer solutions were prepared at a concentration of 1 g/L test substance and subsequently divided over multiple HPLC vials and placed in a thermostated auto sampler at 12 °C, in the dark. At the moment the test vials were placed in the auto sampler, the first analysis was performed using HPLC-CAD. Subsequent analyses were done on different time intervals to determine the rate of hydrolysis in time.

Duration:

48 h

pH:

4

Temp.:

12 °C

Initial conc. measured:

ca. 1 g/L

Duration:

48 h

pH:

7

Temp.:

12 °C

Initial conc. measured:

ca. 1 g/L

Duration:

48 h

pH:

9

Temp.:

12 °C

Initial conc. measured:

ca. 1 g/L

Number of replicates:

2 concentration series

Positive controls:

yes

Negative controls:

no

Transformation products:

yes

No.:

#1

Details on hydrolysis and appearance of transformation product(s):

Based on the lack of monoperoxy succinic acid and the correct mass balance of succinic acid, it was conclude that the test substance solely hydrolysis into succinic acid at 12 °C. During method development monoperoxy succinic acid was detected, however, this was caused by thermal decomposition.

% Recovery:

0

pH:

4

Temp.:

12 °C

Duration:

48 h

% Recovery:

ca. 33.45

pH:

4

Temp.:

20 °C

Duration:

3 h

% Recovery:

>= 0 - <= 1.5

pH:

7

Temp.:

12 °C

Duration:

48 h

% Recovery:

ca. 72.4

pH:

7

Temp.:

20 °C

Duration:

3 h

% Recovery:

0

pH:

9

Temp.:

12 °C

Duration:

48 h

% Recovery:

ca. 46.2

pH:

9

Temp.:

20 °C

Duration:

3 h

Key result

pH:

4

Temp.:

12 °C

DT50:

> 0 - < 3 h

Type:

(pseudo-)first order (= half-life)

Key result

pH:

7

Temp.:

12 °C

DT50:

> 8 - < 24 h

Type:

(pseudo-)first order (= half-life)

pH:

9

Temp.:

12 °C

DT50:

> 2 - < 3 h

Type:

(pseudo-)first order (= half-life)

Details on results:

The concentration of the test substance could not be determined with enough accuracy to calculate the rate of hydrolysis. Therefore, the increasing concentration of the hydrolysis product, succinic acid, was measured to give an indication on the rate of hydrolysis.
After 48 hours no more test substance was detectable and the succinic acid peak increased significantly. At the start of the test already some succinic acid was present, this is a known impurity from the test substance.

Table 1: Measured concentrations of succinic acid in pH buffer 4.

Sample name	Time	Conc. Series I	Conc. Series II	Mass balance* Series I	Mass balance* Series II
	hours	(mg/L)	(mg/L)	(%)	(%)
buffer pH 4 T=0	0	201.6	334.6	28.3	46.3
buffer pH 4 T=3	3	479.4	476.4	67.2	65.9
buffer pH 4 T=4	4	449.2	549.5	63.0	76.0
buffer pH 4 T=6	6	524.1	546.0	73.5	75.5
buffer pH 4 T=8	8	502.8	525.3	70.5	72.6
buffer pH 4 T=24	24	605.4	652.4	84.9	90.2
buffer pH 4 T=31	31	656.2	696.1	92.0	96.2
buffer pH 4 T=48	48	784.8	808.0	110.0	111.7

* Mass balance was corrected for individual weight amount of initial test substance, correcting for 70.5 % purity.

 

Table 2: Measured concentrations of succinic acid in pH buffer 7.

Sample name	Time	Conc. Series I	Conc. Series II	Mass balance* Series I	Mass balance* Series II
	hours	(mg/L)	(mg/L)	(%)	(%)
buffer pH 7 T=0	0	42.9	120.4	6.0	16.5
buffer pH 7 T=3	3	205.4	193.8	28.7	26.5
buffer pH 7 T=4	4	258.1	239.8	36.1	32.8
buffer pH 7 T=6	6	310.3	313.5	43.4	42.9
buffer pH 7 T=8	8	325.9	332.2	45.6	45.5
buffer pH 7 T=24	24	407.1	413.5	56.9	56.6
buffer pH 7 T=31	31	472.3	475.4	66.1	65.1
buffer pH 7 T=48	48	704.2	759.8	98.5	104.0

* Mass balance was corrected for individual weight amount of initial test substance, correcting for 70.5 % purity.

 

Table 3: Measured concentrations of succinic acid in pH buffer 9.

Sample name	Time	Conc. Series I	Conc. Series II	Mass balance* Series I	Mass balance* Series II
	hours	(mg/L)	(mg/L)	(%)	(%)
buffer pH 9 T=0	0	90.6	100.5	12.7	13.9
buffer pH 9 T=1	1	276.1	271.8	38.7	37.6
buffer pH 9 T=2	2	343.5	341.5	48.1	47.2
buffer pH 9 T=3	3	386.5	386.0	54.2	53.4
buffer pH 9 T=5	5	470.1	449.6	65.9	62.2
buffer pH 9 T=7	7	557.2	505.3	78.1	69.9
buffer pH 9 T=24h	24	661.5	656.3	92.7	90.7
buffer pH 9 T=31h	31	759.0	738.2	106.4	102.0
buffer pH 9 T=48h	48	747.0	771.0	104.7	106.6

* Mass balance was corrected for individual weight amount of initial test substance, correcting for 70.5 % purity.

 

Validity criteria fulfilled:

yes

Conclusions:

The test substance hydrolysed solely into succinic acid, at the test temperature of 12 °C, in all tested buffers at pH 4, 7 and 9. The test substance was completely hydrolyzed after 48 hours, at all tested pH buffers.

Executive summary:

A hydrolysis study with the test item was performed according to OECD 111 and Regulation (EC) No. 440/2008 Method C.7. 1 g/L solutions of the test item in sterilised buffer solutions (pH 4, 7, and 9) were prepared.The spiked buffer solutions were subsequently divided over multiple HPLC vials and placed in a thermostated auto sampler at 12 °C, in the dark.At the moment the test vials were placed in the auto sampler, the first analysis was performed using High Performance Liquid Chromatography (HPLC) combined with aCharged Aerosol Detector (CAD). Subsequent analyses were done on different time intervals up to 48 hours to determine the rate of hydrolysis in time.

The concentration of the test substance could not be determined with enough accuracy to calculate the rate of hydrolysis. Therefore the increasing concentration of the hydrolysis product, succinic acid, was measured to give an indication on the rate of hydrolysis.

Two concentration series with each buffer solution were measured. In all tested solutions at all tested pH levels, the test item was completely hydrolysed to succinic acid after 48 hours. The half-life of the test item at pH 4 is <3 h, at pH 7 is between 8 and 24h and at pH 9 is between 2 and 3 hours. After 48 hours no more test substance was detectable and the succinic acid peak increased significantly. At the start of the test already some succinic acid was present, this is a known impurity from the test substance.

Description of key information

The test substance hydrolysed solely into succinic acid, at the test temperature of 12 °C, in all tested buffers at pH 4, 7 and 9. The test substance was completely hydrolyzed after 48 hours, at all tested pH buffers.

Additional information

A hydrolysis study with the test item was performed according to OECD 111 and Regulation (EC) No. 440/2008 Method C.7. 1 g/L solutions of the test item in sterilised buffer solutions (pH 4, 7, and 9) were prepared.The spiked buffer solutions were subsequently divided over multiple HPLC vials and placed in a thermostated auto sampler at 12 °C, in the dark. At the moment the test vials were placed in the auto sampler, the first analysis was performed using High Performance Liquid Chromatography (HPLC) combined with aCharged Aerosol Detector (CAD). Subsequent analyses were done on different time intervals up to 48 hours to determine the rate of hydrolysis in time.

The concentration of the test substance could not be determined with enough accuracy to calculate the rate of hydrolysis. Therefore the increasing concentration of the hydrolysis product, succinic acid, was measured to give an indication on the rate of hydrolysis.

Two concentration series with each buffer solution were measured. In all tested solutions at all tested pH levels, the test item was completely hydrolysed to succinic acid after 48 hours. The half-life of the test item at pH 4 is <3 h, at pH 7 is between 8 and 24h and at pH 9 is between 2 and 3 hours. After 48 hours no more test substance was detectable and the succinic acid peak increased significantly. At the start of the test already some succinic acid was present, this is a known impurity from the test substance.