bis(diethylamino)-N,N-diethylmethaniminium chloride

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

July 28, 2003 – August 7, 2003

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:

2002

Deviations:

yes

Remarks:

The test solutions were heated at 54°C for 8 days instead of the OECD recommended 50°C for 5 days in order to provide additional supportive data on the hydrolysis of the test substance.

GLP compliance:

yes

Remarks:

OECD GLP

Radiolabelling:

no

Analytical monitoring:

yes

Buffers:

The pH 4 buffer was prepared by mixing 41.0 mL of an acetate buffer (1.155 mL glacial acetic acid in 1.000 L of deionized water; 0.02 M) with 9.0 mL of a 1.64 g/L anhydrous sodium acetate solution or 2.72 g/L trihydrate solution (0.02 M).
The pH 7 buffer was prepared by titrating a 10.93 g/L of MOPS: 3-N-morpholino propanesulfonic acid solution to pH 7.0 with approximately 20 mL of approximately 1.00 N aqueous NaOH.
The pH 9 buffer was prepared by titrating a 1.36 g/L ethanolamine solution (0.02 M) to pH 9.0 with approximately 32 mL of 1.0 M HCl and made up to 1000 mL with deionized water.
Aliquots of all three buffers were further diluted with deionized water to prepare buffers at a concentration of 5 mM. The pH of each of the three diluted buffers was measured, but not adjusted.

Details on test conditions:

A solution of the test substance was prepared by rapidly weighing 365.14 mg of the test substance (to minimize absorption of moisture) and dissolving it in 10.00 mL of deionized water (36.51 mg/mL). This solution was used immediately. Stock solutions of the test substance were prepared by adding 100 microliters of the test substance solution to 20.0 mL of each buffer solution and deionized water in 50-mL polypropylene centrifuge tubes and vortexing. To prepare the test solutions, these stock solutions were aliquotted (1.0 mL) to 1.8-mL screw-cap (Teflon) vials and placed in envelopes. Day 0 test solutions (vials in envelope E0) were immediately stored horizontally (to prevent cracking) at -20°C. The pHs of the remaining stock solutions were measured.

The heated solutions, in envelopes E1, E2, E3, E4, and E7, were placed in the 54°C incubator such that the vials were horizontal to facilitate mixing. The remaining stock solutions in 50-mL polypropylene centrifuge tubes were also placed in the incubator. The time was noted and the rotating mixer was turned on (~1 rps). The calibrated temperature logger, set to log temperatures every 8 minutes, was turned on.

On day 1, after 24 h, E1 was removed from the incubator and placed horizontally at approximately -20°C. Removal time was recorded. This was repeated on day 2 through day 4 and on day 8; each day the appropriate envelope was removed from the incubator and placed at approximately -20°C. The average incubator temperature was 53.5 ± 0.7°C over the first 6 days of the 8 day heating period (due to shortage of temperature logger memory space). The incubator was not observed to malfunction on the 8th (last) day of heating. On day 8, the stock solutions in 50-mL polypropylene centrifuge tubes were removed from the incubator, cooled to approximately 22°C, and their pHs were measured.

Duration:

8 d

pH:

4

Temp.:

54 °C

Duration:

8 d

pH:

7

Temp.:

54 °C

Duration:

8 d

pH:

9

Temp.:

54 °C

Number of replicates:

12 per pH

Preliminary study:

The pHs of the (nominal) pH 4, pH 7, and pH 9 buffer Stock Solutions at the end of the test (after heating for 8 d) were different from their nominal values by not more than 0.3 pH units.

The test material was observed in the Heated Solutions as a HPLC peak at 5.3 min. The corresponding observed test material concentrations in these solutions were between 95 % and 106 % of their initial concentrations, indicating that the extents of test material degradation after heating in buffers for 8 d at 54 °C were less than the OECD threshold of 10 % (OECD, 2002). It was expected that the extents of degradation after heating at the OECD-recommended conditions of 50 °C for 5 d (OECD, 2002) would also be less than 10 %, based on the general principle that reaction rate (of a thermal reaction) is directly proportional to temperature, and the extent of a reaction (% conversion) is directly related to time (McQuarrie, 1984).

Based on these results, the test material was found to be hydrolytically stable at pH 4, pH 7, and pH 9, as defined by the OECD, i.e., less than 10 % degradation of the test material was observed after 8 d at 54 °C, indicating that its half-life was greater than 1 year at 25 °C.

Transformation products:

not measured

Key result

pH:

4

Temp.:

25 °C

DT50:

> 1 yr

Key result

pH:

7

Temp.:

25 °C

DT50:

> 1 yr

Key result

pH:

9

Temp.:

25 °C

DT50:

> 1 yr

Details on results:

No further testing was required as less than 10 % of the reaction was observed after 5 days in accordance with the OECD 111 Guidelines.

Observed Test Substance Concentrations in Test Solutions

Label^a	HPLC Area	Test Sbustance Conc. (micrograms/mL)	Average^b	Deviation	% RD	% of Initial Test Substance Conc.^c	Heating Time (days)
9-0a	1830	183.0	182.3	0.7	0.4	--	0.0
9-0b	1817	181.6				--	0.0
9-1a	1828	182.8	181.4	1.4	0.8	100	1.0
9-1b	1801	180.0				99	1.0
9-2a	1801	180.0	NA			99	2.0
9-2b^d	1063	103.2				57^d	2.0
9-3a	1813	181.3	180.3	1.0	0.5	99	3.0
9-3b	1794	179.3				98	3.0
9-4a	1890	189.3	186.1	3.2	1.7	104	4.0
9-4b	1829	182.9				100	4.0
9-7a	1836	183.6	183.8	0.1	0.1	101	7.7
9-7b	1838	183.9				101	7.7
4-0a	1876	187.8	189.0	1.2	0.6	--	0.0
4-0b	1899	190.2				--	0.0
4-1a	1853	185.5	183.6	1.8	1.0	98	1.0
4-1b	1818	181.8				96	1.0
4-2a	1859	186.1	182.6	3.5	1.9	98	2.0
4-2b	1792	179.1				95	2.0
4-3a	1813	181.3	186.1	4.8	2.6	96	3.0
4-3b	1906	190.9				101	3.0
4-4a	1823	182.4	182.6	0.2	0.1	96	4.0
4-4b	1828	182.8				97	4.0
4-7a	1831	183.2	191.4	8.2	4.3	97	7.7
4-7b	1990	199.7				106	7.7
7-0a	1851	185.2	185.5	0.3	0.1	--	0.0
7-0b	1856	185.8				--	0.0
7-1a	1883	188.5	185.4	3.2	1.7	102	1.0
7-1b	1822	182.2				98	1.0
7-2a	1836	183.6	183.0	0.6	0.3	99	2.0
7-2b	1824	182.5				98	2.0
7-3a	1827	182.7	183.5	0.8	0.4	98	3.0
7-3b	1841	184.2				99	3.0
7-4a	1855	185.7	185.2	0.5	0.2	100	4.0
7-4b	1847	184.8				100	4.0
7-7a	1826	182.6	183.9	1.3	0.7	98	7.7
7-7b	1851	185.2				100	7.7
Average: 1.0 %
^a4-, 7-, and 9- indicate pH 4, pH 7, and pH 9, respectively; -0 solutions were frozen, other solutions were incubated at 54°C and then moved to frozen storage at the specified sampling interval prior to analysis. ^baverages of a and b duplicates ^cinitial concentration is the average of the corresponding -0 duplicate samples ^dthe result for this sample was assumed to be an outlier, which appeared to be due to an injection error based on chromatogram features

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of this study, the test material was found to be hydrolytically stable at pH 4, pH 7, and pH 9.

Executive summary:

The hydrolytic stability of the test material was investigated in accordance with the standardised guidelines OECD 111, under GLP conditions. 

The OECD hydrolysis screening test was conducted in which test material solutions in buffers (pH 4, 7, and 9) were heated at 54 ± 1 °C for up to 8 days. The HPLC results indicated that the concentrations of test material at the end of the heating period were between 96 % and 106 % of their initial concentrations, indicating
that the extents of test material degradation during heating were less than the OECD threshold of 10 % (half-life > 1 year at 25 °C).

Under the conditions of this study, the test material was found to be hydrolytically stable at pH 4, pH 7, and pH 9.

Description of key information

Under the conditions of this study, the test material was found to be hydrolytically stable at pH 4, pH 7, and pH 9.

Key value for chemical safety assessment

Half-life for hydrolysis:

1 yr

at the temperature of:

25 °C

Additional information

The hydrolytic stability of the test material was investigated in accordance with the standardised guidelines OECD 111, under GLP conditions. The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).

The OECD hydrolysis screening test was conducted in which test material solutions in buffers (pH 4, 7, and 9) were heated at 54 ± 1 °C for up to 8 days. The HPLC results indicated that the concentrations of test material at the end of the heating period were between 96 % and 106 % of their initial concentrations, indicating
that the extents of test material degradation during heating were less than the OECD threshold of 10 % (half-life > 1 year at 25 °C).

Under the conditions of this study, the test material was found to be hydrolytically stable at pH 4, pH 7, and pH 9.