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Clinical Pharmacy-Pharm D Level Three 2 Semester 2024/2025 Pharmaceutical Technology (PT 607)

Microscopical determination of particle size

Where
d mean = mean particle diameter
n = number of particle in each size range

d = mean size range
Problem 1
The following data were obtained from particle size analysis for a sample of

powder by use of the microscope, calculate the mean particle diameter.
Number of particles in
Size range in micron
each size range(n)
0.5-1.0 2

1.0-1.5 10
1.5-2.0 22

2.0-2.5 54

2.5-3.0 17

3.0-3.5 8
3.5-4.0 5
Solution

Mean of size Number of
Size range in range (d) in particles in each nd
micron
micron size range(n)
0.5-1.0 0.75 2 1.5

1.0-1.5 1.25 10 12.5
1.5-2.0 1.75 22 38.5

2.0-2.5 2.25 54 121.5

2.5-3.0 2.75 17 46.75

3.0-3.5 3.25 8 26
3.5-4.0 3.75 5 18.75

Ʃn= 118 Ʃnd= 265.5
d mean = 265.5 / 118 = 2.25 µm.

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