Reaction products of N-Phenyl-1-Naphthylamine with Nonene, branched

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:

09-14-2021 - 11-04-2021

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

CAS No.: 63451-49-0
Purity: 100% UVCB
Identity: confirmed
Homogeneity: Homogenous by visual identification
Storage stability: Expiry date: 14 Jan 2024
Date of production: 15 Jan 2021
Chemical Name: 1-Naphthalenamine, N-(nonylphenyl)-
Physical state/appearance:
liquid, high viscous / brown to red
Water solubility: At 20.0 °C ± 0.5 °C 0.7 μ/L ± 0.5 μg/L for tests with 0.1

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

Inoculum (activated sludge) was collected on 2nd November 2021 from the aeration tank of the wastewater treatment plant of Lambsheim, Germany.
A suitable aliquot of the activated sludge suspension was sieved by a finely woven mesh with a mesh size of about 1 mm.
Subsequently, this sludge suspension was aerated for about 2 days at 22 ±2° C with carbon dioxide free air in order to reduce the inorganic carbon content in the blank controls.
At the day of exposure, the aeration was stopped, and the sludge suspension was washed once using drinking water and was allowed to settle. After settling, the supernatant was discarded. The remaining sludge suspension was filled up once more with drinking water and the final concentration of the sludge was adjusted to 6.0 g/L dry weight. Aliquots of 7.5 mL of this suspension were added to the 2 L test vessels containing 1.5 L test medium to obtain a final activated sludge concentration of 30 mg/L dry weight.

Duration of test (contact time):

3 h

Initial conc.:

20 mg/L

Based on:

TOC

Remarks:

20 mg/L TOC nominal, equiv. to approx. 23 mg/L test substance

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

The following test assays were prepared: 2 blank control assays (BC)
2 test substance assays (TS)
1 inhibition control test assay (IH)
1 reference substance assay (RS)
The used mineral medium complies with the test guideline OECD 301B
It was prepared as follows:
Solution A: KH2PO4 : 8.50 g
K2HPO4 : 21.75 g
Na2HPO4 × 2 H2O : 33.40 g
NH4Cl : 0.50 g
The compounds were dissolved with deionized water to 1000 mL; the pH value was adjusted to 7.4.
Solution B: CaCl2 × 2 H2O : 36.40 g
The compound was dissolved with deionized water to 1000 mL
Solution C: MgSO4 × 7 H2O : 22.50 g
The compound was dissolved with deionized water to 1000 mL
Solution D: FeCl3 × 6 H2O : 0.25 g
The compound was dissolved with deionized water to 1000 mL
15 mL solution A, 1.5 mL solution B, 1.5 mL solution C and 1.5 mL solution D was used for the preparation of the test assays.
Carbon dioxide (CO2) evolution test was performed in 2L incubation bottles filled up to a
volume of 1.5L.
On the 0th day of exposure, the required volumes of deionized water and the solutions for mineral medium were added to these incubation bottles. Required amount of test substance was weighed small glass plates (microscope cover slips) at a final concentration of 20 mg/L TOC, for the test substance assays as well as inhibition control. Subsequently, the test substance including the weighing plates were added to the corresponding test bottles.
Because of poor water solubility of the test substance, these bottles were treated for few minutes in an ultrasonic bath to ensure an even distribution of test substance in the test medium. Finally, adequate aliquots of reference substance stock solution (aniline) were added at a final concentration of 20 mg TOC/L to the reference test bottle as well as to the inhibition control bottle.
After setting up the test system, pH-values of each of the test vessels were measured and adjusted to 7.4 ±0.2, if necessary. Aliquots of activated sludge suspension (7.5 mL) were added to all bottles at a concentration of 30 mg/L dry weight. The bottles were then connected to two serial scrubbing bottles filled with 100 mL of 0.05 mol sodium hydroxide (NaOH) solution which act as the trap to capture the carbon dioxide evolved from the mineralization processes. Aeration was started on the 0th day of exposure using carbon dioxide free air at a flow of approximately 800 mL per hour by connecting the test bottles with an aeration unit. The incubation bottles were stirred during the experimental duration on a magnetic stirrer.
The amount of CO2 bound in NaOH is determined as TIC (Total Inorganic Carbon) and is a direct measure for the mineralized carbon of the test substance, after subtraction of the blank values. Usually twice a week, the total inorganic carbon (TIC) values were measured from each test vessel. At each time point, NaOH solution from the CO2 capture trap that is directly connected to the incubation botte was used for the calculation of the produced carbon dioxide between two consecutive sampling points. When this first trap is removed from its position for sampling, the second trap was moved forward and connected directly to the test bottles. The emptied trap for TIC sampling was again filled with fresh sodium
hydroxide solution and placed into the second position. The TIC-value of the freshly prepared sodium hydroxide solution was also determined to correct the background values.
Samples for DIC-measurement (validity criterion) from the blank control assays were taken on the 0th day. Since the test substance was poorly soluble in water, no DOC-measurements could be performed from any of the bottles of test assays.
At the end of exposure (28th day), after routine TIC sampling from the NaOH trap near to the test bottle, pH was measured from each of the test assays. After this, each test vessel was acidified with 2 mL of concentrated hydrochloric acid in order to strip out the remaining dissolved CO2 in the test medium. The aeration was continued for another 24 hours and the released CO2 from the test medium during this period was captured into both traps of each test vessels. The TIC content from both NaOH traps was measured after 24 hours and was taken into account for the calculation of degree of biodegradation of 28th day.

Reference substance:

aniline

Key result

Parameter:

% degradation (CO2 evolution)

Value:

0

Sampling time:

28 d

Details on results:

0% CO2/ThCO2 (mean value) based on the maximum level of biodegradation observed in two replicates after an exposure period of 28 days.

Results with reference substance:

Degree of biodegradation of the reference substance
after 14 days: 81% CO2/ThCO2

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

The test item was tested for biodegradation in an OECD 301 B test system. After 28 d incubation , 0% CO2 - evolution could be detected. Therefore, the test item is regarded to be non biodegradable under the chosen conditions.

Description of key information

The test item was tested for biodegradation in an OECD 301 B test system. After 28 d incubation , 0% CO2 - evolution could be detected. Therefore, the test item is regarded to be non biodegradable under the chosen conditions.

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater