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Particle size distribution (Granulometry)

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Reference
Endpoint:
particle size distribution (granulometry)
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:
OECD Guideline 110 (Particle Size Distribution / Fibre Length and Diameter Distributions)
Principles of method if other than guideline:
In consideration of the relevance of granulometry study on toxicological assessment, only the size distributions of the sieved fraction < 100 µm were studied in detail.
GLP compliance:
no
Type of method:
sieving
Remarks:
tested by scanning electron microscopy
Type of distribution:
counted distribution
Percentile:
D50
Mean:
24 µm
Remarks on result:
other: Migrated from fields under 'Mass median diameter' as D50 percentile. No source field for Standard deviation.

The sample was first sieved by a 100µm sieve.

weighted sample:              1.0674 g

weight fraction < 100µm:   0.1009 g

mass fraction < 100µm:       9.45 %

The mass fraction < 100µm was 2.09 %, and was investigated by scanning electron microscopy. The median aspect ratio was 1.67 with 0.80 as standard deviation.

The median diameter of the particle size is given for the fraction < 100µm. The value 25 µm was calculated for cubical and 24 µm for spherical paritcles.

   spherical volume  cubical volume
 particle size  mass fraction  mass fraction
 < 4µm  0.25 %  0.17 %
 4 - 10 µm  4.66 %  3.78 %
 10 - 100 µm  95.09 %  96.06 %
 median diameter  24 µm  25 µm
Conclusions:
Particle size distribution of 2,2`-dithiobis(benzothiazole) was determined by scanning electron microscopy method, giving a median diameter of 24 µm with the main fraction of 96 % distribution in the range of 10 to 100 µm.
Executive summary:

According to OECD guideline 110, the particle size distribution of 2,2`-dithiobis(benzothiazole) was determined by scanning electron microscopy method for the sieved fraction (< 100 µm, 9.45 % of total sample) and presented on the basis of calculated mass fractions. The median diameter was 24 µm with the main fraction of 96 % distribution in the range of 10 to 100 µm (Currenta, 2010); and hence the tested 2,2`-dithiobis(benzothiazole) particles with sieved size smaller than 100 µm are mainly dominated by inhalable fraction as defined in EN 481.

Description of key information

According to OECD guideline 110, the particle size distribution of 2,2`-dithiobis(benzothiazole) was determined by scanning electron microscopy method for the sieved fraction (< 100 µm, 9.45 % of total sample) and presented on the basis of calculated mass fractions. The median diameter was 24 µm with the main fraction of 96 % distributing in the range of 10 to 100 µm (Currenta, 2010); and hence the tested 2,2`-dithiobis(benzothiazole) particles with sieved size smaller than 100 µm are mainly dominated by inhalable fraction as defined in EN 481.

Additional information

The sample is not free-flowing under dry conditions. Sieve fractions tend to form agglomerates of acicular primary particles.

The sample has been chose as a worst case which are available from the manufactures in EU.