(8α,9R,8'''α,9'''R)-1,1'-[(2,3,5,6-tetrafluoro-1,4-phenylene)bis(methylene)]bis(6'-methoxycinchonan-1-ium-9-ol) dibromide

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2020-12-02 until 2021-08-10

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:

April 2004

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

Refer to sampling table below.

Buffers:

Refer to buffer table below.

Details on test conditions:

Refer to study design table below.

Duration:

5 d

pH:

4

Temp.:

50 °C

Initial conc. measured:

108.6 mg/L

Duration:

5 d

pH:

7

Temp.:

50 °C

Initial conc. measured:

108.5 mg/L

Duration:

5 d

pH:

9

Temp.:

50 °C

Initial conc. measured:

105.9 mg/L

Number of replicates:

Triplicate samples at each time point

Positive controls:

no

Negative controls:

no

Remarks:

(Control samples for pH measurement and sterility were prepared.)

Preliminary study:

A preliminary Tier 1 test at 50°C was carried out at a nominal concentration of 100 µg/mL for 5 days at pH 4, 7 and 9 in the dark.

Test performance:

For Tier 1 hydrolysis experiments, triplicate test vessels with 1 mL of buffer solution were prepared for each sampling time. The test item was applied using a solution in water/acetonitrile 80:20 (v/v). The amount of co-solvent added to the aqueous buffer samples was <1% (v/v). For each pH, aliquots of 1.0 mL of the treated buffer solution were transferred into each 1.5 mL screw capped glass vial using a pipette. The actual treatment rate was determined by measuring the concentration in each sample immediately after treatment (0 DAT) using HPLC-UV. Samples were placed in a water bath maintained at 50°C in the dark. At the sampling intervals of 2 days and 5 days, the samples were removed from the water bath and were analysed without dilution on the day of sampling by HPLC-UV.
The pH of the buffer solutions was determined before the incubation and at the last sampling interval (5 DAT).

Transformation products:

no

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

The hydrolysis of the substance was investigated in a preliminary test at 50°C and pH 4, 7 and 9. This study demonstrated that the substance was hydrolytically stable at all three pH conditions tested since less than 10% degradation was observed after 5 days at 50°C.

Key result

Remarks on result:

hydrolytically stable based on preliminary test

Details on results:

The concentration of the substance remained relatively stable at 50°C, over the 5 day incubation period. The mean recovery of the test item based on the nominal treatment rate varied during the incubation from 108.6% to 109.1% at pH 4, from 108.5% to 109.4% at pH 7 and from 105.9% to 97.4% at pH 9, respectively. Since less than 10% degradation was observed after 5 days at 50°C, the test substance was considered to be hydrolytically stable and Tier 2 experiments were not carried out.

The temperatures remained constant throughout the incubation periods of 5 days (50.0±0.5°C) and there was no significant variation in the pH values of the buffered solutions. The samples also remained sterile throughout the study.

Concentrations of the substance expressed in µg/mL and mean recovery percentage expressed in % of the nominal concentration (100 µg/mL).

a) pH 4 buffer

Condition	Replicate	Concentration [µg/mL] after incubation time in days
		0	2	5
pH 4	1	107.56	109.30	107.54
	2	110.38	110.52	109.04
	3	107.91	109.97	110.85
	Mean	108.62	109.93	109.14
	Mean Recovery [%] nominal]	108.6	109.9	109.1

Note: Replicate 2 with 110.38 mg/mL > 110% recovery, but without impact, as no hydrolysis occurred.

 

b) pH 7 buffer

Condition	Replicate	Concentration [µg/mL] after incubation time in days
		0	2	5
pH 7	1	107.85	111.69	109.72
	2	108.44	111.24	109.17
	3	109.10	108.87	109.23
	Mean	108.46	110.60	109.37
	Mean Recovery [%] nominal]	108.5	110.6	109.4

Note: after 2 days of incubation, mean recovery value > 110%, but without impact, as no hydrolysis occurred.

 

c) pH 9 buffer

Condition	Replicate	Concentration [µg/mL] after incubation time in days
		0	2	5
pH 9	1	108.25	106.62	96.90
	2	105.24	105.16	97.97
	3	104.21	103.84	97.31
	Mean	105.90	105.21	97.39
	Mean Recovery [%] nominal]	105.9	105.2	97.4

 

Validity criteria fulfilled:

yes

Conclusions:

Since less than 10% degradation was observed after 5 days at 50°C, the substance was considered to be hydrolytically stable at pH 4, 7, and 9.

Executive summary:

The hydrolysis of the substance was investigated under GLP to the OECD TG 111. The study was performed at a concentration of 100 µg/mL in the dark in sterile aqueous buffered solutions at pH 4 [citrate buffer], pH 7 [phosphate buffer] and pH 9 [borate buffer] at 50°C for 5 days. Triplicate samples from each pH were analysed at zero time and after 2 and 5 days incubation at 50°C. The aqueous solutions were analysed directly by high performance liquid chromatography with UV-detection (HPLC-UV) using a method validated in accordance with SANCO/3029/99 rev 4. The temperature remained constant throughout the incubation period of 5 days (50.0±0.5°C) and there was no significant variation in the pH values of the buffered solutions. The samples also remained sterile throughout the study. The concentration of the substance remained relatively stable at 50°C over the 5 day incubation period: At 50°C, over 5 days, the mean recovery of the test item based on the nominal treatment rate varied from 108.6% at day 0 to 109.1% at pH 4, from 108.5% to 109.4% at pH 7 and from 105.9% to 97.4% at pH 9, respectively. As less than 10% degradation occurred at all pHs during the initial investigation, the substance was determined to be hydrolytically stable and no further testing was conducted.

Description of key information

At 50°C, over 5 days, less than 10% degradation occurred at the test pH values of 4, 7 and 9 during the initial investigation. The substance was determined to be hydrolytically stable and no further testing was conducted.