Page 93 - Practical Technology 2025

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

Problem
Determine the maximum resolution in (nm) achieved through an oil immersion

lens of numerical aperture 1.4 using an incident light of 380 nm.

Solution:

NA= 1.4
λ= 380nm
d= (0.61 x λ)/ NA
d= (0.61x380)/ 1.4

=165.57 nm

Manual Optical Microscopy

Advantages Disadvantages

1. Relatively inexpensive 1. Time consuming - high operator

2. Detect aggregates fatigue - few particles examined
3. Each particle individually 2. No information on 3D shape
examined, 2D shape, color, 3. Certain amount of subjectivity

4. Small sample sizes required associated with sizing - operator
bias

2. Scanning Electron Microscope.

Resolving Power (limit of resolution) of electron microscope:

The minimum distance existing between two objects when these objects can
still be observed as separate objects .

d= 0.753/α√

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