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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:
key study
Study period:
Not stated
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Qualifier:
no guideline followed
Principles of method if other than guideline:
Particle size investigated using laser diffraction technology.
GLP compliance:
not specified
Type of method:
Laser scattering/diffraction
Remarks on result:
not determinable because of methodological limitations
Remarks:
No particle size measurements were available because the test material was soluble in water.
Remarks on result:
not determinable because of methodological limitations
Remarks:
no particle size measurements were available because the test material was soluble in water.
Conclusions:
Under the conditions of the study, no particle size measurements were available because the test material was soluble in water.
Executive summary:

The analysis was carried out on a Microtrac S3500 which uses laser diffraction technology. 500 µL of detergent (TSPP 5 %) was added to improve the distribution of the material in the solvent distilled water. The suspension of the material was treated ultrasonically to destroy potential agglomerates. Particle size determination was conducted in triplicate and the average taken.

Under the conditions of the study, no particle size measurements were available because the test material was soluble in water.

Endpoint:
particle size distribution (granulometry)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
01 August 2017 to13 October 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Guideline:
other: European Commission Technical Guidance Document EUR 20268 'Determination of Particle Size Distribution, Fibre Length and Diameter Distribution of Chemical Substances’
Version / remarks:
2002
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of method:
cascade impaction
Type of particle tested:
primary particle
Type of distribution:
mass based distribution
Remarks on result:
not determinable because of methodological limitations
Remarks:
Too few particles were of a size less than 10.0 μm to allow accurate assessment of the mass median aerodynamic diameter.
No.:
#1
Size:
< 10 µm
Distribution:
<= 0.81 %
No.:
#2
Size:
< 5.5 µm
Distribution:
<= 0.239 %

Table 2: Results of the Sieving Screening Test

Measurement

Result

Mass of test material transferred to sieve (W1)

10.72 g

Mass of test material passed through sieve (W3 – W2)

10.69 g

Percentage of test material less than 100 μm

99.7 %

 

Table 3: Results of the Cascade Impactor

Collection Stage

Particle Size Range Collected (µm)

Collected Mass (g)

Determination 1

Determination 2

Determination 3

Artificial Throat

N/A

0.39

0.16

0.14

Sample Cup 1

>10.0

2.4879

2.7548

2.6385

Sample Cup 2

5.5 to 10.0

0.0177

0.0063

0.0124

Sample Cup 3

2.4 to 5.5

0.0040

0.0009

0.0028

Sample Cup 4

1.61 to 2.4

0.0004

0.0000

0.0027

Sample Cup 5

0.307 to 1.61

0.0000

0.0001

0.0006

Final Filter

<0.307

0.0014

0.0012

0.0006

Total mass of collected test material

2.9014

2.9233

2.7976

Mass of test material added

3.0209

2.9866

3.0109

 

Table 4: Table to show the cumulative amounts of test material collected in the three determinations for the individual particle size cut-points

Particle Size Cut Points (μm)

Cumulative Mass (g)

Cumulative Percentage (%)

Determination 1

Determination 2

Determination 3

Determination 1

Determination 2

Determination 3

<10.0

0.0235

0.0085

0.0191

0.810

0.291

0.683

<5.5

0.0058

0.0022

0.0067

0.200

0.075

0.239

<2.4

0.0018

0.0013

0.0039

0.062

0.044

0.139

<1.61

0.0014

0.0013

0.0012

0.048

0.044

0.043

<0.307

0.0014

0.0012

0.0006

0.048

0.041

0.021

 

- Overall cumulative percentage with a particle size less than 10.0 μm: ≤ 0.810 %

- Overall cumulative percentage with a particle size less than 5.5 μm: ≤ 0.239 %

Sampling for the cascade impactor determinations was performed by rolling the test material container for approximately 10 minutes then sampled from the top, middle and bottom. The overall results from the cascade impactor were taken as limit values due to the variation between the sampling positions; this gives a worst case scenario. Too few particles were of a size less than 10.0 μm to allow accurate assessment of the mass median aerodynamic diameter.

The inhalable fraction is defined as the mass fraction of particles which can be inhaled by nose or mouth, the thoracic fraction is defined as the mass fraction of particles that passes the larynx and the respirable fraction is defined as the mass fraction of particles that reaches the alveoli.

 

Table 5: Summary of Results

Measurement

Method

Result

Percentage of test material with an inhalable particle size <100 μm

Sieve

99.7 %

Percentage of test material with a thoracic particle size <10.0 μm

Cascade Impactor

0.810 %

Percentage of test material with a respirable particle size <5.5 μm

Cascade Impactor

0.239 %

Conclusions:
Under the conditions of this study, the proportion of test material having an inhalable particle size <100 μm was 99.7 % from the sieving method. The overall cumulative percentage with a thoracic particle size less than 10.0 μm: ≤ 0.810 % and the overall cumulative percentage with a respirable particle size less than 5.5 μm: ≤ 0.239 %.
Executive summary:

The particle size distribution of the test material was determined in accordance with the standardised guideline of the European Commission Technical Guidance Document EUR 20268 Determination of Particle Size Distribution, Fibre Length and Diameter Distribution of Chemical Substances, under GLP conditions.

The test material was first subjected to a screening test using sieving apparatus and then a cascade impactor was used for the main test.

Sampling for the cascade impactor determinations was performed by rolling the test material container for approximately 10 minutes then sampled from the top, middle and bottom. The overall results from the cascade impactor were taken as limit values due to the variation between the sampling positions; this gives a worst case scenario. Too few particles were of a size less than 10.0 μm to allow accurate assessment of the mass median aerodynamic diameter. The inhalable fraction is defined as the mass fraction of particles which can be inhaled by nose or mouth, the thoracic fraction is defined as the mass fraction of particles that passes the larynx and the respirable fraction is defined as the mass fraction of particles that reaches the alveoli.

The proportion of test material having an inhalable particle size <100 μm was 99.7 % from the sieving method. The overall cumulative percentage with a thoracic particle size less than 10.0 μm: ≤ 0.810 % and the overall cumulative percentage with a respirable particle size less than 5.5 μm: ≤ 0.239 %.

Description of key information

Fox, 2018

The proportion of test material having an inhalable particle size <100 μm was 99.7 % from the sieving method. The overall cumulative percentage with a thoracic particle size less than 10.0 μm: ≤ 0.810 % and the overall cumulative percentage with a respirable particle size less than 5.5 μm: ≤ 0.239 %.

Additional information

Fox, 2018

The particle size distribution of the test material was determined in accordance with the standardised guideline of the European Commission Technical Guidance Document EUR 20268 Determination of Particle Size Distribution, Fibre Length and Diameter Distribution of Chemical Substances, under GLP conditions. The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).

The test material was first subjected to a screening test using sieving apparatus and then a cascade impactor was used for the main test.

Sampling for the cascade impactor determinations was performed by rolling the test material container for approximately 10 minutes then sampled from the top, middle and bottom. The overall results from the cascade impactor were taken as limit values due to the variation between the sampling positions; this gives a worst case scenario. Too few particles were of a size less than 10.0 μm to allow accurate assessment of the mass median aerodynamic diameter. The inhalable fraction is defined as the mass fraction of particles which can be inhaled by nose or mouth, the thoracic fraction is defined as the mass fraction of particles that passes the larynx and the respirable fraction is defined as the mass fraction of particles that reaches the alveoli.

The proportion of test material having an inhalable particle size <100 μm was 99.7 % from the sieving method. The overall cumulative percentage with a thoracic particle size less than 10.0 μm: ≤ 0.810 % and the overall cumulative percentage with a respirable particle size less than 5.5 μm: ≤ 0.239 %.

Flatschacher, 2017

The analysis was carried out on a Microtrac S3500 which uses laser diffraction technology. 500 µL of detergent (TSPP 5 %) was added to improve the distribution of the material in the solvent distilled water. The suspension of the material was treated ultrasonically to destroy potential agglomerates. Particle size determination was conducted in triplicate and the average taken.

Under the conditions of the study, no particle size measurements were available because the test material was soluble in water.