Potassium trifluoroacetate

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 1991-09-05 to 1991-11-28

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study performed according to international guideline (EEC, ISO and OECD) and GLP. All validity criteria were fulfilled.

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1992

Report date:

1992

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

Deviations:

yes

Remarks:

Minor deviations: Instead of an effluent/extract/mixture, activated sludge was used as an inoculum, ammonium chloride was omitted from the medium to prevent nitrification and the testing period was extended up to 77 days.

Test guideline 2

Qualifier:

according to guideline

Guideline:

ISO 7827 (Evaluation in an Aqueous Medium of the "Ultimate" Aerobic Biodegradability of Organic Compounds - Method by Analysis of Dissolved Organic Carbon (DOC))

Version / remarks:

ISO/TC 147/SC 5WG 4N152

Deviations:

not specified

Test guideline 3

Qualifier:

according to guideline

Guideline:

other: EEC, 1984: "Official Journal of the European Communities" L251, 1984.09.19. Part C. Methods for the determination of ecotoxicity, method C.6. Degradation-biotic degradation : Closed bottle test

Deviations:

not specified

GLP compliance:

yes (incl. QA statement)

Remarks:

1992-11-27

Test material

Test material information

Constituent 1

Reference substance name:

Sodium trifluoroacetate

EC Number:

220-879-6

EC Name:

Sodium trifluoroacetate

Cas Number:

2923-18-4

Molecular formula:

C2HF3O2.Na

IUPAC Name:

sodium trifluoroacetate

Test material form:

solid

Details on test material:

- Name of test material (as cited in study report): Trifluoroacetic acid, sodium salt (CAS 2923-18-4 / EC 220-879-6)

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
Sodium trifluoroacetate and potassium trifluoroacetate have the same chemical structure. Only the associated cation Na instead of K are different.
The available data, including basic physico-chemical properties and ecotox data, confirm that the read-accross approach is justified, because the two substances present the same profile.

PHYSICO-CHEMICAL PROPERTIES of Sodium trifluoroacetate
- Molecular formula: C2F3O2Na
- Molecular weight: 136 g/mol
- Smiles notation (if other than submission substance): C(C(=O)[O-])(F)(F)F.[Na+]
- Substance type: salt
- Melting point: 207 - 209°C
- Boiling point: no data
- Vapour pressure: 0.00268 Pa at 25°C (highest calculated value from EPIsuite)
- Water solubility : 625 g/L (no data on the method)
- log Pow: -3.31 (KOWWIN estimation)
- pKa: no data, but it is a salt of the same acid than TFAK.
- Stability of test material at room temperature: stable under test conditions
- pH dependance on stability: no data

OTHER PROPERTIES (if relevant for this endpoint)
- Adsorption characteristics: based on log kow and low logKoc, low potential of adsorption
- Toxicity to microorganisms: no

See the endpoint study summary "Environmental fate and pathways" for the read-across justification.

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Secondary activated sludge was obtained from the WWTP Nieuwgraaf in Duiven. The WWTP Nieuwgraaf is an activated sludge plant treating predominantly domestic wastewater. A minor deviation of the test procedures described in the guidelines was introduced: Instead of an effluent/extract/mixture, activated sludge was used as an inoculum.
- Laboratory culture: No data
- Method of cultivation: no data
- Storage conditions: no data
- Storage length: no data
- Preparation of inoculum for exposure: The sludge was diluted to a concentration of 2 mg DW/L in the closed bottles
- Pretreatment: The activated sludge was preconditioned to reduce the endogenous respiration rates: the sludge (approximately 200 mg Dry Weight (DW)/L) was aerated for a period of one week.
- Concentration of sludge: 2 mg DW/L
- Initial cell/biomass concentration: no data
- Water filtered: Deionized water containing no more than 0.01 mg Cu/l and 1 mg/l non-purgeable organic carbon was prepared in an Elgastat water purification system (Elga, Breukelen, The Netherlands).
- Type and size of filter used, if any: The dry weight (DW) of the inoculum was determined by filtrating 100 mL of the activated sludge over a preweighed 8 µm Schleicher and Schüll filter. This filter was dried for 1.5 hours at 104°C and weighed after cooling. DW was calculated by subtracting the weighed filters.

Duration of test (contact time):

77 d

Initial test substance concentration

Initial test substance concentration 1

Initial conc.:

20 mg/L

Based on:

test mat.

Initial test substance concentration 2

Initial conc.:

0.12 other: mg/mg

Based on:

other: ThOD

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: 8.5mg/l KH2PO4, 21.75mg/l K2HPO4, 33.3mg/l Na2HPO4.2H2O, 22.5mg/l MgSO4.7H2O, 27.5mg/l CaCl2, 0.25mg/l FeCl3.6H2O. Ammonium chloride was omitted from the medium to prevent nitrification. Due to this omission the pH of the medium decreased slightly.
- Additional substrate: none
- Solubilising agent (type and concentration if used): none
- Test temperature: The temperature was measured and recorded with a control one (IBT, Rotterdam, The Netherlands). The bottles were incubated at 21+/- 1°C.
- pH: The pH was measured using a pH meter, Consort P207.
- pH adjusted: no
- CEC (meq/100 g): not specified
- Aeration of dilution water: no
- Suspended solids concentration: not specified
- Continuous darkness: yes
- Other: none

TEST SYSTEM
- Culturing apparatus: the test was performed in 250 to 300 ml BOD (biological oxygen demand) bottles with glass stoppers.
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: not specified
- Method used to create anaerobic conditions: not applicable
- Measuring equipment: oxygen electrode (WTW Trioxmatic EO 200) and meter (WTW OXI 530).
- Test performed in closed vessels due to significant volatility of test substance: no
- Test performed in open system: no
- Details of trap for CO2 and volatile organics if used: not applicable
- Other: none

SAMPLING
- Sampling frequency: 0, 7, 14, 21, 28, 42, 77 days
- Sampling method: two duplicates bottles of all series were withdraw for analyses of the dissolved oxygen concentrations. The close bottle test was prolonged by measuring the course of the oxygen decrease in the bottles of day 28 using a special funnel. This funnel fitted exactly in the BOD bottle. Subsequently, the oxygen electrode was inserted the BOD bottle to measure the oxygen concentration. The medium dissipated by the electrode was collected in the funnel. After withdrawal of the oxygen electrode the medium collected flowed back into the BOD bottle, followed by removal of the funnel and closing of the BOD bottle.
- Sterility check if applicable: no
- Sample storage before analysis: no
- Other: none

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes in duplicate
- Abiotic sterile control: No
- Toxicity control: No
- Other: Mineral nutrient solution without test material but with inoculum and mineral nutrient solution with sodium acetate and with inoculum.

Reference substance

Reference substance:

acetic acid, sodium salt

Remarks:

6.7 mg/L (ThOD = 0.8 mg/mg)

Results and discussion

Test performance:

Temperatures ranged from 23 to 25°C instead of 22 +/- 1°C but this deviation is not suspected to have modified the performance of the test. The results of the prolonged test are invalid because the differences of extremes of replicate values of the removal of the test chemical at 77 days are 95% ( > 20%) : see table 1 in "any other information on results incl. tables" field.

% Degradation

% Degradation 1

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

28 d

Remarks on result:

other: also 7 and 21 days

% Degradation 2

Parameter:

% degradation (O2 consumption)

Value:

8

Sampling time:

14 d

Remarks on result:

other: also at 42 days

Details on results:

The pH of the media was 7.0 at the start of the test and 7.1 at day 28.Trifluoroacetic acid, sodium salt is not biodegraded in the prolonged closed bottle test (See table 1, table 2 in "Any other information on results incl. tables" field, and figure 1 in "Attached document" field) and should therefore not be classified as readly biodegradable. The biodegradation percentage at day 77 in the prolonged closed test was 0.

BOD5 / COD results

Results with reference substance:

The concentration of sodium acetate in the bottles was 6.7 mg/L. ThOD of sodium acetate = 0.8 mg/mg.
See table 1, table 2 in "Any other information on results incl. tables" field, and figure 1 in "Attached document" field

Any other information on results incl. tables

Table 1 : Dissolved oxygen concentrations (mg/L) in the closed bottles

Time (days)	Oxygen concentration (mg/L)
	Oc	Oa	Ot
0   Mean (M) 7   Mean (M) 14   Mean (M) 21   Mean (M) 28   Mean (M) 42   Mean (M) 77   Mean (M)	8.2 8.2 8.2 7.6 7.6 7.6 7.8 7.7 7.8 7.0 6.9 7.0 6.6 7.3 7.0 3.6 5.4 4.5 0.1 1.3 0.7	8.2 8.2 8.2 3.4 3.2 3.3 2.9 3.0 3.0 2.5 2.6 2.6 2.1 3.3 2.7 - - - - - -	8.2 8.2 8.2 7.6 7.7 7.7 7.6 7.6 7.6 7.0 7.0 7.0 6.7 7.3 7.0 3.8 4.7 4.3 0.1 2.0 1.1

Table 2 : Oxygen consumption (mg/L) and the percentages biodegradation (BOD/ThOD) of Trifluoroacetic acid, sodium salt and sodium acetate in the closed bottle test

Time (days)	Oxygen consumption (mg/L)		Biodegradation (%)
	Test	Acetate	Test	Acetate
0 7 14 21 28 42 77	0.0 0.0 0.2 0.0 0.0 0.2 0.0	0.0 4.3 4.8 4.4 4.3 - -	0 0 8 0 0 8 0	0 83 92 85 83 - -

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

The validity criteria were all fulfilled

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

A ready biodegradability test was performed which allows the biodegradability to be measured in an aerobic aqueous medium. The ready biodegradability was determined in the closed bottle test performed according to slightly modified OECD 301D, EEC 1984 Part C., and ISO Test Guidelines. Trifluoroacetic acid, sodium salt was not biodegraded in the closed bottle test (28 days and prolonged) and should therefore not be classified as readily biodegradable.

Executive summary:

In order to assess the biotic degradation, a ready biodegradability test was performed which allows the biodegradability to be measured in an aerobic aqueous medium. The ready biodegradability was determined in the closed bottle test performed according to slightly modified OECD 301D, EEC 1984 Part C., and ISO Test Guidelines. Microorganisms (Secondary activated sludge at concentration of 2 mg DW/L, obtained from the WWTP Nieuwgraaf in Duiven: plant treating predominantly domestic wastewater) are inoculated into a chemically defined liquid medium containing the test substance (Trifluoroacetic acid, sodium salt at 20 mg/L) or the reference substance (Acetic acid, sodium salt or Sodium acetate at 6.7 mg/L) under aerobic conditions for a period of 77 days; the test was prolonged because the pass level was not reached at day 28. Use was made of 10 bottles containing only inoculum, 10 bottles containing test substance and inoculum, and 10 bottles containing sodium acetate and inoculum. The temperature and pH was measured, temperatures ranged from 23 to 25°C and the pH of the media was 7.0 and 7.1 at the start and the end of the test, respectively. Two duplicate bottles of all series were withdrawn for analyses of the dissolved oxygen concentration using an oxygen electrode at day 0, 7, 14, 21, 28, 42 and 77 days. Parameter followed for degradation estimation was O2 consumption.

The percentages biodegradation of Trifluoroacetic acid, sodium salt in the closed bottle test were 0% for 0, 7, 21, 28 and 77 days and 8% for 14 and 42 days. However, the results of the prolonged test are invalid because the differences of extremes of replicate values of the removal of the test chemical at 77 days are 95% ( > 20%). Moreover, the result of 8% degradation at day 42 is probably an artefact due to the 40 % coefficient of variation between duplicate values of the control.

The percentages biodegradation of sodium acetate in the closed bottle test were 0, 83, 92, 85 and 83% for 0, 7, 14, 21 and 28 days respectively. The test substance caused no reduction in the endogenous respiration. Therefore, Trifluoroacetic acid, sodium salt is considered to be non-inhibitory to the inoculum. Trifluoroacetic acid, sodium salt was not biodegraded in the closed bottle test (28 days) and should therefore not be classified as readily biodegradable.