Lithium [ethanedioato-O,O’]tetrafluorophosphate

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 2019-09-17 to 2019-10-17

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2019

Report date:

2019

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Version / remarks:

1992

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Lithium [ethanedioato-O,O’]tetrafluorophosphate

EC Number:

826-676-4

Cas Number:

521065-36-1

Molecular formula:

LiPF4C2O4

IUPAC Name:

Lithium [ethanedioato-O,O’]tetrafluorophosphate

Specific details on test material used for the study:

Batch No.: 190722
Purity: > 99 wt%

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: activated sludge freshly obtained from a municipal sewage treatment plant: 'Waterschap Aa en Maas', 's-Hertogenbosch, The Netherlands, receiving predominantly domestic sewage.
- Treatment: Freshly obtained sludge was kept under continuous aeration until further treatment. Before use, sludge was coarsely sieved (1 mm). After treatment concentration of suspended solids (SS) was determined to be 3 g/L in concentrated sludge as used for the test. Magnetically stirred sludge was used as inoculum at an amount of 3 mL per litre of mineral medium, leading to a SS concentration of 9 mg/L.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial test substance concentration 1

Initial conc.:

101 mg/L

Based on:

test mat.

Initial test substance concentration 2

Initial conc.:

12 mg/L

Based on:

TOC

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Test duration: 28 days for inoculum blank and test item (last CO2 measurement on Day 29). 14 days for procedural and toxicity control (last CO2 measurement on Day 15). During the test period, test media were aerated and stirred continuously.
- Test vessels: 2 litre brown coloured glass bottles.
- Milli-RO water: Tap-water purified by reverse osmosis (Milli-RO) and subsequently passed over activated carbon.
- Stock solutions of mineral components: A) 8.50 g KH2PO4, 21.75 g K2HPO4, 67.20 g Na2HPO4.12H2O, 0.50 g NH4Cl, dissolved in Milli-RO water and made up to 1 litre, pH 7.4 ± 0.2; B) 22.50 g MgSO4.7H2O dissolved in Milli-RO water and made up to 1 litre. C) 36.40 g CaCl2.2H2O dissolved in Milli-RO water and made up to 1 litre. D) 0.25 g FeCl3.6H2O dissolved in Milli-RO water and made up to 1 litre.
- Mineral medium: 1 L mineral medium contains: 10 mL of solution (A), 1 mL of solutions (B), (C), (D), and Milli-RO water.
- Illumination: Test media were excluded from light.
- Test temperature: 22-23 °C
- pH: At the start of the test: 7.4-7.6; Day 14: 7.3-7.8; Day 28: 7.1-7.5
- pH adjusted: yes, Adjusted using 1 M HCl for Blank control and Procedural control

TEST SYSTEM
- Pre-incubation medium: Before the start of the test (Day -1) mineral components, Milli-RO water (ca. 80 % of final volume) and inoculum were added to each bottle. This mixture was aerated with synthetic air overnight to purge the system of CO2.
- Type and number of bottles: Test suspension: containing test item and inoculum (2 bottles). Inoculum blank: containing only inoculum (2 bottles). Procedural control: containing procedural control item and inoculum (1 bottle). Toxicity control: containing test item, procedural control item and inoculum (1 bottle).
- Preparation: At the start of the test (Day 0), test and procedural control item were added to bottles containing microbial organisms and mineral components. Volumes were made up to 2 L with Milli-RO water, resulting in the mineral medium described before. Three CO2-absorbers (bottles filled with 100 mL 0.0125 M Ba(OH)2) were connected in series to the exit aeration line of each test bottle.

MEASUREMENTS AND RECORDINGS
- pH: At the start of the test (Day 0) and on the penultimate day (Day 14 for procedural and toxicity control and Day 28 for inoculum blanks and test item), before addition of concentrated HCl.
- Temperature of medium: Continuously in a vessel with Milli-RO water in the same room.

Reference substance

Reference substance:

acetic acid, sodium salt

Results and discussion

Test performance:

1. Procedural control item was biodegraded by at least 60 % (actual result: 85 %) within 14 days.
2. Difference between duplicate values for %-degradation of test item was less than 20 % at the end of the 10-day window, but increased to 24 % by the end of the test. It was decided to evaluate the value at the end of the 10-day window to assess the validity of the test.
3. Total CO2 release in the blank at the end of the test did not exceed 40 mg/L (57.9 mg CO2 per 2 litres of medium, corresponding to 29 mg CO2/L).
4. Inorganic Carbon content (IC) of test item (suspension) in mineral medium at the beginning of the test was less than 5 % of the Total Carbon content (TC). Since test medium was prepared in tap-water purified by reverse osmosis (Milli-RO water (Millipore Corp., Bedford, Mass., USA, carbon levels < 500 ppb)), IC was less than 5 % of TC (mainly coming from the test item, 12 mg TOC/L).

% Degradation

Parameter:

% degradation (CO2 evolution)

Value:

>= 87 - <= 111

Sampling time:

28 d

Details on results:

Relative biodegradation values calculated from measurements performed during the test period revealed 87 % and 111 % biodegradation of test item, for vessel A and B, respectively (based on ThCO2). Furthermore, average biodegradation of test item in vessel A and B reached ≥60 % within a 10-day window.
In the toxicity control, more than 25 % biodegradation occurred within 14 days (84 %, based on ThCO2). Therefore, the test item was considered not to inhibit microbial activity.
Functioning of the test system was checked by testing the procedural control item sodium acetate, which showed a normal biodegradation curve.

BOD5 / COD results

Results with reference substance:

It biodegraded by at least 60 % (actual result: 85 %) within 14 days.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The test item was readily biodegradable under the conditions of the modified Sturm test

Executive summary:

The ready biodegradability for test item in aqueous medium with microbial activity introduced by inoculation with activated sludge was evaluated in compliance with OECD 301B.

The test item was tested in duplicate at a target concentration of 101 mg/L, corresponding to 12 mg TOC/L. The study consisted of six bottles: 2 inoculum blanks (no test item), 2 test bottles (test item), 1 procedural control (sodium acetate) and 1 toxicity control (test item plus sodium acetate). Test duration was 28 days for inoculum blank and test item (last CO2 measurement on Day 29) and 14 days for procedural and toxicity control (last CO2 measurement on Day 15).

Relative biodegradation values calculated from measurements performed during the test period revealed 87 % and 111 % biodegradation of test item, for vessel A and B, respectively (based on ThCO2). Furthermore, average biodegradation of test item in vessel A and B reached ≥60 % within a 10-day window.

In the toxicity control, the test item was considered not to inhibit microbial activity.

Since all criteria for acceptability of the test were met, this study was considered to be valid.

In conclusion, the test item was readily biodegradable under the conditions of the modified Sturm test.