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Particle size distribution (Granulometry)

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Description of key information

The particle size distribution shows not single peaks, but a continuous distribution starting at approximately 30 µm, leaving fractions of less than 10% below 40 µm and more than 70% above 100 µm. No particles smaller than 10 µm were detected, therefore, it can be assumed that the inhalative toxicity doesn’t have to be tested. 

Additional information

Theparticle size distribution of the test item was determined by sedimentation following ISO 13317-2 – Fixed Pipette Method

The determination was performed in duplicate, using a saturated solution in H2O as suspending medium.

The measured values show good reproducibility, giving a deviation of less than 20% for all particle sizes.

The particle size distribution shows not single peaks, but a continuous distribution starting at approximately 30 µm, leaving fractions of less than 10% below 40 µm and more than 70% above 100 µm. No particles smaller than 10 µm were detected, therefore, it can be assumed that the inhalative toxicity doesn’t have to be tested.

As the homogenised sample gave a mean deviation of 55% (pre-test) resp. 24 or 16% (main studies) from the theoretical value (following weight used and volume sampled), it should be kept in mind that the particle size distribution which is given in this report applies to only 45% resp. 76 or 84% of the test item. The remaining parts should be considered as greater than the upper Stokes diameter.

In the following table 3, the values of both experiments and the respective mean as well as the difference in % is stated:

Table 3: Comparison Experiments 1 and 2

Stokes-Diameter

Experiment 1

Experiment 2

Mean

Difference in %

µm

%

%

 

 

103.81

27.5%

24.3%

25.9%

3.2%

72.19

22.9%

21.3%

22.1%

1.6%

50.17

11.1%

12.4%

11.8%

1.3%

40.23

7.8%

7.7%

7.8%

0.2%

36.56

3.3%

4.7%

4.0%

1.5%

33.54

2.0%

1.2%

1.6%

0.8%

30.99

1.3%

0.0%

0.7%

1.3%

28.79

0.0%

0.0%

0.0%

0.0%