Sodium bis(trifluoromethylsulfonyl)imide

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

September 2021

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Purity/Assay: 99.9%

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge: Nanjing Tiebei Sewage Treatment Plant) (Batch No.: AS20210702
- Preparation of inoculum for exposure: The sludge was washed with basal mineral salt medium (BSM) by settling the sludge in a graduated cylinder, decanting the supernatant liquid, replacing with fresh BSM, aerating, and settling. The above washing process was repeated 3 times and was aerated until use.
Before use, the sludge was centrifuged one time (5000 r/min, 10 minutes) and the supernatant liquid decanted. Thereafter, a small amount of the washed sludge was weighed and then dried at 100 °C until the weight of the dried sludge did not change significantly anymore.
- Concentration of sludge: Then the dry weight percentage of suspended solids (p) of the activated sludge was calculated to be 7.84%. Finally, 5.10 g wet sludge after centrifugation was mixed with 100 mL BSM (Batch No.: BSM20210709) to obtain an activated sludge with a mixed liquor suspended solids level of 4.00 g SS/L.
- Initial cell/biomass concentration: Cell density was determined to be 4.5 × 107/L using microscope.

Duration of test (contact time):

28 d

Initial conc.:

600 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Culturing apparatus: test substance stock solution, reference control stock solution and inoculum solution were added to the test vessels, and finally made up to 250 mL with BSM. All vessels contained a Teflon-coated magnetic stir bar for consistency. The equipment was assembled, the stirrer was started, and the equipment was checked for air-tightness
- Number of culture flasks/concentration: 6, The test was performed in 510 mL BOD bottles
- Composition of medium: Basal mineral salt medium (BSM). All stock solutions were stored in the dark at 2~8 °C
- Test temperature: 21.6 ~ 22.9 °C
- pH: 7.17 ~ 7.67
- Suspended solids concentration: 4.00 g SS/L
- Continuous darkness: yes

TEST SYSTEM
- Number of culture flasks/concentration: 2
- Measuring equipment: Automatic respirometer (BOD meter)

SAMPLING
- Sampling frequency: start (0 days) and end (28 days)

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2
- Toxicity control: 1
- procedure control: 1

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

ca. 0

Sampling time:

28 d

Records of Oxygen Uptake

Time (d)	Oxygen uptake (mg O2/L)
	Inoculum control		Test suspension		Procedure control	Inhibition control
	#3	#4	#1	#2	#5	#6
0	0.00	0.00	0.00	0.00	0.00	0.00
1	2.80	4.20	2.80	1.40	35.2	26.8
2	4.20	4.20	5.60	1.40	52.1	56.4
3	5.60	7.00	7.00	5.60	56.4	60.6
4	5.60	7.00	7.00	5.60	62.0	63.4
5	7.00	8.50	8.50	7.00	67.6	69.0
6	8.50	9.90	9.90	9.90	73.3	71.9
7	9.90	9.90	11.3	12.7	76.1	74.7
8	9.90	11.3	12.7	14.1	76.1	77.5
9	12.7	11.3	14.1	14.1	77.5	78.9
10	14.1	14.1	15.5	16.9	78.9	81.7
11	15.5	15.5	16.9	18.3	81.7	81.7
12	16.9	16.9	18.3	19.7	83.1	83.1
13	16.9	16.9	18.3	19.7	83.1	83.1
14	16.9	18.3	18.3	19.7	83.1	84.5
15	16.9	19.7	16.9	19.7	84.5	83.1
16	18.3	19.7	18.3	19.7	84.5	84.5
17	18.3	19.7	18.3	19.7	84.5	84.5
18	18.3	19.7	18.3	19.7	84.5	83.1
19	18.3	19.7	18.3	19.7	84.5	84.5
20	18.3	21.1	18.3	21.1	84.5	84.5
21	19.7	22.5	18.3	21.1	86.0	86.0
22	19.7	22.5	19.7	21.1	86.0	87.4
23	19.7	22.5	19.7	21.1	86.0	87.4
24	21.1	22.5	21.1	22.5	87.4	87.4
25	21.1	22.5	21.1	22.5	87.4	87.4
26	21.1	22.5	21.1	22.5	87.4	87.4
27	21.1	24.0	21.1	24.0	88.8	88.8
28	21.1	24.0	21.1	24.0	88.8	88.8

Biodegradation Results

Time (d)	Biodegradation (%)
	Test suspension			Procedure control	Inhibition control
	#1	#2	Mean	#5	#6
0	0.00	0.00	0.00	0.00	0.00
1	-1.10	-3.30	-2.20	47.5	17.9
2	2.20	-4.40	-1.10	71.7	40.0
3	1.10	-1.10	0.00	75.0	41.6
4	1.10	-1.10	0.00	83.4	43.8
5	1.18	-1.18	0.00	89.6	47.0
6	1.10	1.10	1.10	96.0	48.1
7	2.20	4.40	3.30	99.1	49.7
8	3.30	5.50	4.40	98.1	51.3
9	3.30	3.30	3.30	98.1	51.3
10	2.20	4.40	3.30	97.0	51.8
11	2.20	4.40	3.30	99.1	50.8
12	2.20	4.40	3.30	99.1	50.8
13	2.20	4.40	3.30	99.1	50.8
14	1.10	3.30	2.20	98.1	51.3
15	-2.20	2.20	0.00	99.1	49.7
16	-1.10	1.10	0.00	98.1	50.2
17	-1.10	1.10	0.00	98.1	50.2
18	-1.10	1.10	0.00	98.1	49.2
19	-1.10	1.10	0.00	98.1	50.2
20	-2.20	2.20	0.00	97.0	49.7
21	-4.40	0.00	-2.20	97.2	49.8
22	-2.20	0.00	-1.10	97.2	50.8
23	-2.20	0.00	-1.10	97.2	50.8
24	-1.10	1.10	0.00	98.2	50.3
25	-1.10	1.10	0.00	98.2	50.3
26	-1.10	1.10	0.00	98.2	50.3
27	-2.36	2.20	-0.080	99.1	50.8
28	-2.36	2.20	-0.080	99.1	50.8

 

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

not biodegradable under test conditions. percentage biodegradation was -0.08 % after 28 days.

Executive summary:

According to “The guidelines for the testing of chemicals”, SEPA (HJ/T 153-2004), “The Guidelines for the Testing of Chemicals, Degradation and Accumulation” (2^nd edition), Beijing: China Environmental Press. 2013, “Chemicals - Readybiodegradability - Manometric respirometry test” (GB/T 21801-2008); and with reference to Procedure 301F of the “Guidelines for Testing of Chemicals” of the OECD: “Manometric Respirometry Test” (17, July, 1992), the ready biodegradability of SODIUM BIS(TRIFLUOROMETHYLSULFONYL)IMIDE was determined in a 28-day oxygen consumption test (OECD 301F) using activated sludge from a domestic waste water treatment plant as the source of the microbial inoculum.

The initial concentration of the test substance in the test vessels was 600 mg/L. The microbial inoculum concentration (mixed liquor suspended solids) SS was 30.0 mg/L.

During the test, the temperature was kept at 21.6~ 22.9 °C. The pH value of the content in the test container was maintained between 7.17 and 7.67. The average total oxygen uptake in the inoculum blank was 22.6 mg O₂/L at the end of the study, within the normal range of 20 ~30 mg O₂/L. Biodegradation of the reference substance, sodium benzoate, reached 98.1% at14 days (> 60%). The maximum difference of parallel degradation rate of test substance was 6.60% (< 20%) during the study. Biodegradation of inhibition control was 51.3% at 14 days (> 25%), and the oxygen consumption by the test substance was greater than 60% of inoculum blank during the test period, indicating that there was no inhibition effect to inoculum. Thus, the test was considered valid.

Under the valid conditions, biodegradation of the test substance (SODIUM BIS(TRIFLUOROMETHYLSULFONYL)IMIDE) was -0.080% at the end of the 28-day study.

Description of key information

A recent reliable study is available on the target substance, NaTFSI. According to the Procedure 301F of the “Guidelines for Testing of Chemicals” of the OECD: “Manometric Respirometry Test” (17, July, 1992), the ready biodegradability of SODIUM BIS(TRIFLUOROMETHYLSULFONYL)IMIDE was determined in a 28-day oxygen consumption test (OECD 301F) using activated sludge from a domestic waste water treatment plant as the source of the microbial inoculum.

Under the valid conditions, biodegradation of the test substance (SODIUM BIS(TRIFLUOROMETHYLSULFONYL)IMIDE) was -0.080% at the end of the 28-day study.

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable