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Particle size distribution (Granulometry)

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Endpoint:
particle size distribution (granulometry)
Data waiving:
other justification
Justification for data waiving:
other:
Endpoint:
particle size distribution (granulometry)
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
06 July 2010- 07 July 2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
This study has been performed according to OECD and international guidelines, and according to GLP principles. The test substance is adequately characterised. Therefore full validation applies.
Qualifier:
according to guideline
Guideline:
OECD Guideline 110 (Particle Size Distribution / Fibre Length and Diameter Distributions)
Deviations:
no
Qualifier:
according to guideline
Guideline:
ISO 13320 (Particle size analysis - Laser diffraction methods)
Version / remarks:
2009
Deviations:
no
Qualifier:
according to guideline
Guideline:
other: CIPAC MT 187
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of method:
Laser scattering/diffraction
Type of particle tested:
primary particle
Type of distribution:
volumetric distribution
Mass median aerodynamic diameter:
281 µm
Geometric standard deviation:
4.58
Percentile:
D10
Mean:
< 57.1 µm
St. dev.:
0.76
Percentile:
D50
Mean:
< 201 µm
St. dev.:
3.14
Percentile:
D90
Mean:
< 488 µm
St. dev.:
9.81

Standard visual observation

Sample observed to be a coarse, white powder.

Observation at 100 x magnification

The particles appeared to crystalline and of irregular shape. The smallest individual particle size was approximately 15 μm and the largest individual size was approximately 597 μm.

Observation at 400 x magnification

The sample was observed to be made up of single crystalline particles.

Manual Sieve Analysis

Manual sieve analysis indicated that 100% by weight of the sample had a particle size of < 2000 µm. Therefore the sample was tested as received.

Laser diffraction

 run n°  1  2  3  4  5  Average*  SD  RSD**
 d10  56.254  58.238  56.287  57.063 57.566   57.064  0.76  1.33%
 d50  197.068  206.622  199.600  201.398  201.760  201.286  3.14  1.56%
 d90 477.392   484.893 502.818   497.346 480.671   488.148  9.81  2.01%
 MMAD  275.191  288.532  278.727  281.238  281.743  281.08  4.39  1.56%
 GSD  129.650  143.488  133.067  135.166  136.324    4.58  3.38%

* Average result was calculated from the entirety of data captured in each run and is not a simple arithmetic mean.

** Coefficient of variation for d50 is less than 3%; d10 and d90 are less than 5%. Thus repeatability of the characteristic particles in the size distribution are within the acceptable limits as per the ISO 13320 test standard.

The graph of volume % versus particle diameter shows a Gaussian-type distribution.

For the thresholds relevant to inhalation potential:

Inhalable fraction (< 100.237 μm): 21.75 %

Thoracic fraction (< 10.024 μm): 0.75 %

Respirable fraction (< 4.477 μm): 0.04 %

A threshold of 500 μm is generally assumed to be of concern for dust explosion potential; the corresponding corrected fraction (< 502.377 μm) accounts for 90.1%.

Conclusions:
The test substance contains a limited fraction of particles fine enough to be inhaled and reach the thoracic fraction.
Dust explosion potential should be considered.
Executive summary:

The test substance was first examined under microscope, and described as a coarse white powder, consisting of single crystalline particles, of irregular shape.

Manual sieve analysis indicated that 100% by weight of the sample had a particle size of < 2000 µm. Therefore the sample was tested as received.

Using the laser diffraction test (dry method), the distribution was Gaussian, with a Mass Median Aerodynamic Diameter (MMAD) of 281 µm.

With regard to inhalation potential, about 22% of total particles are smaller than 100 μm, and ca 0.75% could reach the thoracic fraction (<10 μm).

Fine particles relevant to dust explosion hazard (<500 μm) account for 90%.

Description of key information

From the various processes of the individual registrants, particle size distribution can show different profiles. Therefore the CSA was performed for both high and low dustiness parameter, and the individual data are not deemed necessary.

Additional information

Experimental data is provided as supporting information on the representative sample tested for physico-chemical properties.