branched and cross-linked multi-walled carbon nanotubes

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Data waiving:

other justification

Justification for data waiving:

other:

Cross-reference

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Endpoint:

dispersion stability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

17th - 19th February 2021

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

OECD Guideline 318 (Dispersion Stability of Nanomaterials in Simulated Environmental Media)

GLP compliance:

no

Remarks:

It is not required for this study to be conducted to GLP

Type of method:

dynamic light scattering

Specific details on test material used for the study:

Athlos 200 Carbon Nanostructures

Analytical monitoring:

no

Details on test sample/test medium:

The sonic probe (Vibra Cell (Sonics) Ultrasonic Probe – 13 mm probe with replaceable tip) was calibrated to run at approximately 40 Watts, as per OECD Test 318
12.5 mg sample was weighed into a 250 mL beaker and Water for Injection (WFI) was added dropwise to form a paste. The mixture was sealed in the beaker with nesco-film and left at ambient for approximately 26 hours.
• The sample paste was diluted with 125 mL WFI to make an approximate concentration of 100 mg/L. Temperature of the medium 22.9°C.
• An ice bath was set up using a 2 Litre beaker and the sample beaker was held in the bath with a retort stand. Temperature of the medium 3.7°C.
• The sonic probe was inserted centrally into the sample medium at a depth of approximately 2.5 cm. The sample was sonicated for 10 minutes, Amplitude 60%, Energy 250 kJ.
• The sample beaker was carefully removed and placed against a white background to observe. A piece of filter paper was placed over the beaker to exclude dust.

OBSERVATIONS
• T = 0 mins – Initially, the bulk of the sample appeared irregularly aggregated/agglomerated, held in suspension in the WFI, with a layer of sample also held on the surface of the water. Between these two layers, a water layer with no free particulate was apparent.
• T = 10; 20; 30; 40; 50 mins – There was no perceptible change in appearance or state throughout these timepoints.
• T = 17 hours – Left at ambient overnight, there was no perceptible change. A light was placed behind and underneath the beaker, which made the water layer and sample
aggregation/agglomeration more distinct.
No free particulate was observed in the water, and the sample had a highly irregular macrostructure.

Remarks on result:

not determinable

Athlos 200 Carbon Nanostructures sample solution did not form a homogeneous dispersion. Therefore, it is not possible to take a representative subsample for DLS analysis.

Conclusions:

Post-sonication at approximately 40 Watts, the 100 mg/L Athlos 200 Carbon Nanostructures sample solution did not form a homogeneous dispersion. Therefore, it is not possible to take a representative subsample for DLS analysis.

Executive summary:

A study was conducted to OECD 318 guidelines to determine the dispersion stability of Athlos 200 Carbon Nanostructures. It was determined that post-sonication at approximately 40 Watts, the 100 mg/L Athlos 200 Carbon Nanostructures sample solution did not form a homogeneous dispersion. Therefore, it is not possible to take a representative subsample for DLS analysis.