Zinc oxide

Nanomaterial Zeta potential

Administrative data

Endpoint:

nanomaterial Zeta potential

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2021

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

significant methodological deficiencies

Remarks:

Study lacks detailed documentation.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2021

Report date:

2021

Materials and methods

Test guideline

Qualifier:

no guideline available

Principles of method if other than guideline:

The zeta potential of two zinc oxide nanos (T0420 uncoated and T0421 hydrophobic coated) was investigated via electrophoresis. All measurements were carried out in a Zetasizer Nano from Malvern in the pH range from 3 to 10. The measured particle sizes and the Henry equation were used to convert the measured mobilities into the zeta potentials.

GLP compliance:

not specified

Type of method:

electrophoresis

Details on methods and data evaluation:

All measurements were carried out in the Zetasizer Nano from Malvern in the pH range from 3 to 10. The measurements were started at the pH value that the samples had after dilution. The pH was adjusted using HCl or NaOH. The samples were measured in 10 mmol / l KCl.
For better dispersion, the samples were treated in an ultrasonic bath for 2 minutes before the measurement. After a standing time of at least 5 minutes, the samples for the measurements were taken from the supernatants. The very large particles sediment too quickly and otherwise interfere with the measurement.
The measured particle sizes and the Henry equation were used to convert the measured mobilities into the zeta potentials.

Sampling:

The samples were measured in 10 mmol / l KCl. For better dispersion, the samples were treated in an ultrasonic bath for 2 minutes before the measurement. After a standing time of at least 5 minutes, the samples for the measurements were taken from the supernatants.

Test material

Test material information

Constituent 1

Reference substance name:

Zinc oxide

EC Number:

215-222-5

EC Name:

Zinc oxide

Cas Number:

1314-13-2

Molecular formula:

ZnO

IUPAC Name:

oxozinc

Test material form:

solid: nanoform, no surface treatment

Details on test material:

- Particle size distribution: D10 is 10.4 nm ; D50 is 18.2 nm ; D90 is 28.2 nm
- Shape of particles: spheroidal
- Surface area of particles: ca. 10 - 40 m2/g
- Crystal structure: hexagonal zincite crystalline phase
- Coating: no coating applied
- Dustiness: 12 mg/kg (respirable mass index)
- Dissolution rate (kmin): 378 ng/cm2/h

Specific details on test material used for the study:

Zinc Oxide T0420 (uncoated) and Zinc Oxide T0421 (hydrophobic) nanomaterials were used for this study

Results and discussion

Zeta potential

Zeta potential:

22 mV

pH:

7

Remarks on result:

other: St. dev. and medium not specified

Isoelectric point

Isoelectric Point:

10.5

Remarks on result:

other: St. dev. and medium not specified

Any other information on results incl. tables

Only sample T0420 could be measured because sample T0421 was too hydrophobic and could not be dispersed in water.
Sample T0420 started at pH 7.7. When titrating into acid, the sample began to dissolve. Below pH7 the sample was completely dissolved.
For the conversion into the zeta potential, the particle size was measured by means of DLS. The peak maximum from the intensity distribution was used.

Applicant's summary and conclusion

Conclusions:

Only sample T0420 could be measured because sample T0421 was too hydrophobic and could not be dispersed in water. The Zeta potential value was +22 mV, the isoelectric point was pH 10.5 and the mobility at pH 7 was +1,6 (μm/s)/V/cm).

Executive summary:

The zeta potential of two zinc oxide nanos (T0420 uncoated and T0421 hydrophobic) was investigated via electrophoresis.

Results:
Only sample T0420 could be measured because sample T0421 was too hydrophobic and could not be dispersed in water. The Zeta potential value was +22 mV, the isoelectric point was pH 10.5 and the mobility at pH 7 was +1,6 (μm/s)/V/cm).