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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:
7 June 2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP compliant guideline study.
Qualifier:
according to guideline
Guideline:
other: BS ISO 13320:2009
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Remarks:
25 February 2009
Type of method:
Laser scattering/diffraction
Type of distribution:
volumetric distribution
Percentile:
D50
Mean:
ca. 35.873 µm
St. dev.:
0.96
Remarks on result:
other: Mass Median Aerodynamic Diameter
Percentile:
D10
Mean:
< 1.756 µm
St. dev.:
0.02
Percentile:
D50
Mean:
< 28.36 µm
St. dev.:
0.76
Percentile:
D90
Mean:
< 274.639 µm
St. dev.:
6.4

The method development phase of the analysis indicated that the most appropriate test and material parameters to obtain the optimum measurement were:

Dispersant : Air

Dispersion pressure : 3 barg

Refractive index (sample) : 0.0 n

Absorption : 0.0 AU

Analysis Model : General Purpose (Normal)

Using the identified parameters, the particle size was analysed over the range 0.02 μm to 2000 μm. Sample particulates were inspected in various solvents but found to agglomerates; therefore dry powder analysis was deemed more suitable. The results of the formal analysis are presented in the table. In addition, a graph of volume (%) versus Particle Diameter (μm), and full particle size distribution, is provided in Graph 8.A (Average of 5 runs).

Table 1. Full test results

  RUN 1 RUN 2 RUN 3 RUN 4 RUN 5 **Average 
Volume weighted Mean 92.260 90.506 86.991 89.611 92.136 90.301
Median (d.50) 29.403 28.745 27.989 28.571 27.149 28.360
Mode (μm) 204.479 202.219 171.821 182.880 208.572 196.171
*MMAD 37.192 36.36 35.403 36.139 34.341 35.873
10 % of material is < 1.775 1.768 1.760 1.767 1.710 1.756
50 % of material is < 29.403 28.745 27.989 28.571 27.149 28.360
90 % of material is < 277.672 273.194 263.605 275.056 283.089 274.639

All results are in μm

* Mass Median Aerodynamic Diameter

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

36.63 % by volume of sample was seen to be < 10.00 μm.

Table 2. Standard Deviation results

Run No.  STDVP  % STDV
d10  1.775 1.768 1.760 1.767 1.710 0.02 1.34
d50  29.403 28.745 27.989 28.571 27.149 0.76 2.68
d90  277.672 273.194 263.605 275.056 283.089 6.40 2.33
d15.78  42.660 42.730 42.680 42.480 43.560 0.38 0.88
GSD  0.689 0.673 0.656 0.673 0.623 0.02 3.38
MMAD  37.192 36.360  35.403 36.139 34.341 0.96 2.68

GSD = Geometric standard deviation STDVP=Standard deviation of the population.

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.

Conclusions:
Particle size distribution of Ash was 0.2 - 2000 µm. The Mass Median Aerodynamic Diameter of Ash was 35.9 µm. By volume, 36.6 % of Ash particles were <10.00 µm.
Executive summary:

Ash particle size distribution was analysed in a GLP laboratory using the standard BS ISO 13320:2009 accordant Laser Diffraction method. Particle size distribution of Ash was determined to be 0.2 - 2000 µm. The Mass Median Aerodynamic Diameter of Ash was 35.9 µm and the volume weighted mean was 90.301 µm. By volume, 36.6 % of Ash particles were smaller than 10.00 µm. The major proportion (90%) of Ash particles were smaller than 275 µm.

Endpoint:
particle size distribution (granulometry)
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
Study was conducted between 4 June 2010 and 7 June 2010
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP, non-guideline experimental investigation
Qualifier:
no guideline followed
Principles of method if other than guideline:
Particle size analysis based on visual, 100x and 400x observations and sieving analysis.
GLP compliance:
yes (incl. QA statement)
Remarks:
25 February 2009
Type of distribution:
volumetric distribution
Percentile:
D50
Mean:
> 3 - < 651 µm
Remarks on result:
other: Microscopic visual observation at 100 x magnification ('Mass median diameter' as D50 percentile. No source field for Standard deviation.)
Size:
> 2 000 µm
Distribution:
0.2 %
Size:
< 2 000 µm
Distribution:
99.8 %

Standard visual observation

Sample observed to be large grey particles which formed clusters. Some particles believed to be > 2000 μm therefore a separate manual sieve analysis was performed.

Observation at 100 x magnification

The particles appeared to be irregular shaped crystals. The smallest mean particle size was approximately 3 μm and the largest mean size was approximately 651 μm.

Observation at 400 x magnification

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

Table 1. Full Test Results from the Manual Sieve Analysis

Sieve size (μm)  Sieve weight (g)  Sieve + powder weight (g)  Powder weight (g)  % by weight 
>2000  325.8  325.9  0.1  0.2 
<2000  241.7  291.6  49.9  99.8 
    TOTALS  50  100 
Conclusions:
Of the Ash particles, 99.8 % were smaller than 2000 µm. According to the optical microscope observation at 100 x magnification, the Ash particles were irregularly shaped with mean sizes between 3 and 651 µm.
Executive summary:

Particle size of Ash was screened visually and with optical microscope observation at 100 x and 400 x magnification. Visually, Ash was observed to consist of grey particles which formed clusters. The more detailed microscopic observation showed irregular shaped particles, of which 99.8 % were smaller than 2000 μm. The smallest mean particle size was approximately 3 μm and the largest mean size was approximately 651 μm.

Description of key information

The particle size distribution of Ash was determined with optical microscope analysis, sieving analysis and Laser Diffraction method. The Laser Diffraction analysis was performed according to BS ISO 13320:2009 standard. The particle size distribution was 0.2 - 2000 µm. The Mass Median Diameter was 35.873 µm and the volume weighted mean was 90.301 µm.

Additional information

Particle size distribution of Ash was determined to be 0.2 - 2000 µm. Totally, 99.8% of the particles fit inside this range. According to the optical microscope observation at 100 x magnification, the Ash particles were irregularly shaped crystals with mean sizes between 3 and 651 µm. On the basis of Laser diffraction analysis, Mass Median Aerodynamic Diameter of Ash was 35.9 µm and volume weighted mean was 90.301 µm. The major proportion (90%) of Ash particles had an aerodynamic diameter smaller than 275 µm. Volumetric proportions of certain smaller particle sizes of Ash are presented in table 1.

Table 1. Volumetric proportions of inhalation toxicologically relevant particle sizes of Ash presented as aerodynamic diameter.

 Particle size (µm)

 % vol

 <100

 68

 <10

 37

 <5

 26

 <1

 5

 <0.1

 0