1,1,2,2,3,3,4,4,4-nonafluoro-N-methylbutane-1-sulfonamide

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: screening test, other

Remarks:

short adhoc aerobic biodegradation experiment conducted for internal method development purposes

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Mar - Apr 2018

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2019

Report date:

2019

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

Test substance was incubated in undiluted return activated sludge. At selected times aliquots were analyzed by HPLC/MS/MS.

GLP compliance:

no

Remarks:

screening level study conducted for internal method development purposes

Test material

Test material information

Constituent 1

Reference substance name:

1,1,2,2,3,3,4,4,4-nonafluoro-N-methylbutane-1-sulfonamide

EC Number:

614-396-3

Cas Number:

68298-12-4

Molecular formula:

C5H4F9NO2S

IUPAC Name:

1,1,2,2,3,3,4,4,4-nonafluoro-N-methylbutane-1-sulfonamide

Specific details on test material used for the study:

- Purity: 97.25%

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Return activated sludge from River Mountains water treatment facility, Henderson, NV USA. Sludge was received on 26 Feb 2018 and used 19 Mar 2018.
- Storage length: 21 days
- Preparation of inoculum for exposure: none, sludge was used as received without dilution.

Duration of test (contact time):

18 d

Initial test substance concentration

Initial conc.:

2.77 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

test mat. analysis

Details on study design:

TEST CONDITIONS
- Composition of medium: Undiluted activated sludge. 20 mL of sludge was placed in a 125 mL flask, loosely capped to allow gas exchange.
- Additional substrate: no
- Solubilising agent: none
- Test temperature: 25 °
- pH: not reported
- pH adjusted: no
- Continuous darkness: not reported

TEST SYSTEM
- Culturing apparatus: Thermo Max-Q temperature controled shaker-incubator
- Number of culture flasks/concentration: one
- Method used to create aerobic conditions: shaking at 150 RPM
- Test performed in open system: yes

SAMPLING
- Sampling frequency: 1 mL samples taken on days 0, 1, 4, 8, 11, 15, and 18.

CONTROL AND BLANK SYSTEM
- Inoculum blank: None
- Abiotic sterile control: Autoclaved sludge, one replicate per substance
- Toxicity control: None

Reference substance

Reference substance:

other: 1,1,2,2,3,3,4,4,4-nonafluoro-N-(2-hydroxyethyl)-N-methylbutane-1-sulfonamide

Remarks:

substance has been previously examined and its biodegradation is well known.

Results and discussion

% Degradation

Parameter:

% degradation (test mat. analysis)

Sampling time:

18 d

Remarks on result:

not determinable because of methodological limitations

Remarks:

mass balance was inadequate to compare loss of parent with degradation products

Details on results:

MeFBSA was incubated with viable activated sludge and autoclaved (sterile) activated sludge. Results are in Tables 1 and 2, respectively. Mass balance at the end of incubation was low in both active and sterile cultures (21 mole% and 4 mole%, respectively). Very little of the starting material could be recovered in both cases (2% and 4%, respectively). Demethylation to form 1,1,2,2,3,3,4,4,4-nonafluoro-1-Butanesulfonamide (major pathway) and deamidation to form perfluorobutanesulfinic acid (minor pathway) are the two degradation pathways, with the acid later oxidizing to form perfluorobutanesulfonic acid.

BOD5 / COD results

Results with reference substance:

As expected, the oxidation of the reference substance terminal group from hydroxyethyl to carboxymethyl was essentially complete by day 1.

Any other information on results incl. tables

Table 1, concentration of MeFBSA and potential metabolites (µM), viable sludge incubation

Day	MeFBSA	FBSA	PFBSi	PFBS	PFBA	Sum	Mass balance
0	6.2	<LOQ	<LOQ	<LOQ	<LOQ	6.2	70%
1	5.85	0.708	0.0198	<LOQ	<LOQ	6.57	74%
4	4.79	1.09	0.0241	<LOQ	<LOQ	5.91	67%
8	2.19	1.42	0.0378	<LOQ	<LOQ	3.65	41%
11	1.25	1.51	0.0413	<LOQ	<LOQ	2.81	32%
15	0.665	1.67	0.042	0.014	<LOQ	2.4	27%
18	0.179	1.61	0.0375	0.0186	<LOQ	1.85	21%
Mole % of dose on day 18	2%	18%	0.40%	0.20%	0%	21%	─

 

Table 2, concentration of MeFBSA and potential metabolites (µM), sterile sludge incubation

Day	MeFBSA	FBSA	PFBSi	PFBS	PFBA	Sum	Mass balance
0	5.75	<LOQ	<LOQ	<LOQ	<LOQ	5.75	65%
1	5.11	<LOQ	<LOQ	<LOQ	<LOQ	5.11	58%
4	3.09	<LOQ	<LOQ	<LOQ	<LOQ	3.09	35%
8	1.9	<LOQ	<LOQ	<LOQ	<LOQ	1.9	22%
11	1.17	<LOQ	<LOQ	<LOQ	<LOQ	1.17	13%
15	0.665	<LOQ	<LOQ	<LOQ	<LOQ	0.665	8%
18	0.371	<LOQ	<LOQ	<LOQ	<LOQ	0.371	4%
Mole % of dose on day 18	4%	0%	0%	0%	0%	4%	─

 

Applicant's summary and conclusion

Validity criteria fulfilled:

not applicable

Interpretation of results:

other: incomplete mass balance, result cannot be interpreted

Conclusions:

MeFBSA is rapidly lost when incubated with viable or sterilized activated sludge.

Executive summary:

MeFBSA biodegradation was assessed by incubating 18 days with undiluted activated sludge. The parent and several expected metabolites were analyzed by LC/MS immediately and on days 1, 4, 8, 11, 15, and 18. An autoclave sterilized sludge control was included. In both cases the parent was almost complete absent by day 18 (2% and 4% residual in viable and sterile incubations). In the viable flask, FBSA and PFBSi appeared at the same approximate times, with PFBS appearing later. However, these degradation products accounted for only 18%, 0.4%, and 0.2% of the starting material. No degradation products were detected in the sterile control.

The study does not establish half-life due to incomplete mass balance. However, as an exploratory study it demonstrates possible degradation pathways through specific chemical analysis. It is considered reliable with restrictions.