1-ethyl-3-methyl-3H-imidazolium dicyanidoamide(1-)

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Activated sludge was colledcted from the Lied Sewage Treatment Plant of Guangzhou
- Preparation of inoculum for exposure: The sludge was removed of any coarse particles and surface impurities and washed with mineral medium. The supernatant liquid phase was decanted and the solid material resuspended in a mineral medium.
A homogenized aliquot of the final sludge suspension was weighted, thereafter dried and the ratio of wet to dry weight was calculated. Based on this ratio (1.7g/L), 471mL of the sludge was centrifuged and the supernatant removed. The wet sludge was resuspended in 100mL mimeral medium to obtain a concentration equivalent to 4.0g dry material per liter. The inoculum was aerated until use. 15mL inoculum was inoculated in each flask to give a final concentration of 30mg/L dry weight.

Duration of test (contact time):

59 d

Initial conc.:

23.3 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: The used mineral medium complies with the test guideline OECD 301 B. (table 1)
Table 1:
Composition of the mineral salts medium.
Stock solution A (pH 7.4): Ammonium chloride, NH4CI (0.50 g), Twelve Hydration Di-sodium hydrogenphosphate, Na2HP04 x 12 H20 (67.15 g), Potassium dihydrogenphosphate, KH2P04 (8.50 g), Di-potassium hydrogenphosphate trihydrate, K2HP04 x 3 H2O (28.5 g), dissolved in 1000 mL deionized water
Stock solution B: Anhydrous calcium chloride, CaCl2 (13.75 g), dissolved in 500 mL deionized water
Stock solution C: Magnesium sulfate heptahydrate, MgS04 x 7 H20 (11.25 g), dissolved in 500 mL deionized water
Stock solution D: Iron (Ill) chloride hexahydrate, FeC13 x 6 H20 (0.125 g), dissoleved in 500 mL deionized water

- Test temperature: 22 ± 2 °C
- Suspended solids concentration: 30 mg/L (dry weight)
- Test substance concentration: 23.3 mg/L
- TOC concentration from test substance: 12.3 mg/L
- Reference substance concentration: 21.0 mg/L
- TOC concentration from test substance: 12.3 mg/L

TEST SYSTEM
- Culturing apparatus: 2000 mL incubation bottles filled up to a vlume of 1.5 L
- Number of culture flasks/concentration: For each test series the following number of test flasks was set up:
Test suspension: Containing test substance and inoculum (4 replicates)
Inoculum blank: Containing only inoculum (2 replicates)
Toxicity control: Containing test substance, reference compound and inoculum (1 replicate)
Procedure control: Containing reference compound and inoculum (1 replicate)
- Method used to create aerobic conditions: CO2-free air at a rate of 30mL/min-100mL/min. All testing systems were stirred.

SAMPLING
- Sampling frequency: The CO2 absorber bottles were sampled on days 2, 5, 8, 11, 14, 23, 29, 34, 43, 48, 53, 56, 60.

ANALYSIS AND DETERMINATION:
- On days of CO2 measurement, the barium hydroxide absorber was disconnected and the hydroxide sloution was titrated with 0.05mol/L HCl using phenolphalein as the indicator. On the 59th day, 1mL of concentrated hydrochloric acid was added to each flask and the test suspension were aerated overnight to drive off the carbon dioxide present in the test suspension. On the 60th day the last analysis of evolved carbon dioxide in the 3 absorption bottles was made.
- 0.0125mol/L barium hydroxide solution was used as the absorbent in the present study. According to the respective titration values of 0.05mol/L HCl, the following formula was used to calculate the weight of CO2 from the test substance:
CO2 produced (mg) = (HCl concentration (mol/L) x [HCl titrated on unabsorbed Ba(OH)2 (mL) - HCl titrated (mL)] x 44)/2.
- % degradation = (CO2 produced (mg)/[TOC addad in test (mg) x 3.67]) x 100
(3.67 is the conversion factor (44/12), and the amount of CO2 produced as accumulated value)

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, 2 flasks
- Toxicity control: yes, 1 flask

Reference substance:

other: Sodium benzoate

Key result

Parameter:

% degradation (CO2 evolution)

Value:

24.7

Sampling time:

59 d

Results with reference substance:

On the 14th day of the test, the percentage degradation of the reference compound sodium benzoate was 73% and the percentage degradation of the toxicity control was 37%.

Interpretation of results:

not readily biodegradable

Description of key information

Not readily biodegradable according to OECD criteria.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

The ready biodegradability of the test substance EMIM Dicynanamid was tested in a GLP guideline study according to OECD 301B (BASF, 2013). The results of this enhanced biodegradation study revealed a biodegradation degree 24.7% based on the CO2 production after a test duration of 59 days. Based on these data, the test substance is considered to be not readily biodegradable but moderately biodegradable.