Optimizing Particle Size Analysis in Pharma: The Role of Sample Dispersion

Particle size analysis is critical in pharmaceutical development, impacting bioavailability, stability, and manufacturing efficiency. Laser diffraction analyzers are widely used for their speed and precision—but the sample dispersion method is key to accurate results.

How Laser Diffraction Works

Laser particle size analyzers measure how dispersed particles scatter light. This scattering pattern reveals the particle size distribution.

Why Dispersion Matters

Improper dispersion can lead to:

• Overestimated particle sizes

• Wider size distributions

• Poor reproducibility

Proper dispersion ensures particles are individually suspended and accurately measured.

Common Dispersion Methods

• Ultrasonic Dispersion: Breaks up agglomerates via cavitation; ideal for fine powders.

• Mechanical Stirring: Keeps particles suspended; less effective alone.

• Chemical Dispersants: Reduce surface tension and prevent re-agglomeration.

• Combined Methods: Ultrasonic + stirring offers the most reliable results.

Case Study: API Testing Results

• Ultrasonic: Narrow, accurate distribution

• Stirring Only: Incomplete dispersion, larger particle size

• Combined Method: Best consistency and minimal agglomeration

Best Practices

✅ Match dispersion technique to sample type
✅ Use ultrasonic + stirring for tough samples
✅ Validate and document dispersion protocols
✅ Monitor dispersion quality regularly

Conclusion

For precise pharmaceutical particle size analysis, high-quality instruments must be paired with effective sample dispersion. A combined ultrasonic and mechanical approach ensures regulatory compliance, product quality, and patient safety.