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Particle size distribution (Granulometry)

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Endpoint:
particle size distribution (granulometry)
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
2007
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
other: Guidance Document JRC, ECB/TM/February 1996
GLP compliance:
yes (incl. certificate)
Type of distribution:
volumetric distribution
Percentile:
D50
Mean:
ca. 500 µm

 Width of  1st sieving     2nd sieving       STD
 mesh  net weight  weight  net weight  weight  mean  dev
 [μm]  [g]  [%]  [g]  [%]  [%]  [%]
 2000  0 0
 1000  6.63 13.14  4.10  8.07  10.61  3.58 
 500  24.08 47.71 27.95  55.04  51.38  5.18 
 250  15.91 31.52  14.42  28.40  29.96  2.21 
 125  3.36 6.66  4.12  8.11  7.39  1.03 
 75  0.56 1.11  0.28  0.55  0.83  0.39 
 < 75  0.04 0.08  0.02  0.08 
Conclusions:
Only 0.02 % (w/w) of the test item were below 75 μm. The approximate mean particle size was 500 µm.
Executive summary:

The test material is a clumpy powder. By visual observation, the particle size of the test item was too big to determine the distribution by laser diffraction method. Based on the visual observation, the sieve method was selected. Only 0.02 % (w/w) of the test item were below 75 μm.

Endpoint:
particle size distribution (granulometry)
Data waiving:
study scientifically not necessary / other information available
Justification for data waiving:
the study does not need to be conducted because the substance is marketed or used in a non solid or granular form
Percentile:
D50
Remarks on result:
other: Migrated from fields under 'Mass median diameter' as D50 percentile. No source field for Standard deviation.

Description of key information

The particle size is not a function of the chemical but a function of the spray dryer or dedusting technique used for formulation. The determination of the particle size of the dried press cake led to an estimated mean particle size of 500 µm by sieving of the clumpy material.

Additional information

The test item is usually isolated by spray drying into the composite microgranular form or dedusting agent is added to form agglomerates of particles. As such, the particle size is not a function of the chemical but a function of the spray dryer and technique used; a typical particle size distribution for reactive dyes isolated as low dust granules is as follows:

10% < 123 µm; 25% < 159 µm; 50% < 207 µm; 75% < 266 µm; 90% < 326 µm

For testing purposes, the test material was isolated as wet press cake and dried. This led to a clumpy material that is usually further milled to allow proper testing of physico-chemical ant (eco)toxicological tests. The dried press cake was investigated for its particle size.

The test material is a clumpy powder; by visual observation, the particle size of the test item was too big to determine the distribution by laser diffraction method. Based on the visual observation, the sieve method was selected. Only 0.02 % (w/w) of the test item were below 75 μm. The approximate mean particle size was 500 µm.