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Diss Factsheets

Administrative data

nanomaterial specific surface area
Type of information:
experimental study
Adequacy of study:
other information
4 (not assignable)
Rationale for reliability incl. deficiencies:
other: Study with accepted scientific standards

Data source

Reference Type:
other company data
Report date:

Materials and methods

Test guideline
according to guideline
other: calculation
Principles of method if other than guideline:
The specific surface area of powders may be determined by the BET gas adsorption
method; however, this method works only with dry powders. For dispersions, where
the particles are suspended in a liquid medium, the gas adsorption method is not
feasible.Thus, for dispersions like Tinosorb A2B, it is standard to calculate the
specific surface area from particle size measurements, assuming spherical particle
shape. From TEM and SEM pictures of Tinosorb A2B it is evident that this
assumption is reasonable [2]. As the milling process is always the same procedure,
these pictures can be regarded as representative.
GLP compliance:
Type of method:
other: calculation

Test material

Constituent 1
Test material form:
solid: nanoform

Results and discussion

Specific surface area
Specific Surface Area:
50.8 m²/g
Remarks on result:
other: average from particle size distribution.

Any other information on results incl. tables

When using the BET method for determination of the specific surface area in dry

powders, an integral value over all particle sizes results, representing the average

over the size distribution of the particles in the dry powder. Because BET is not

appropriate for particle dispersions, the corresponding experiment for an aqueous

dispersion was presented here. We report results from using dynamic light scattering

data for the determination of the particle size distribution of a Tinosorb A2B batch

and transforming those into an average value of the specific surface area of the


Applicant's summary and conclusion

Executive summary:

Asp, Tinosorb A2B = 50.8 m²/g (average from particle size distribution)

This value, derived from the average particle size distribution, is slightly higher than

the value obtained using the median d(0.5). As is known from mathematical

descriptions of distribution functions, the mean or average value for the distribution is

not always the same as the median value for the same distribution function.