Evaluation of Light Intensity Distribution and Particle Size Distribution of Mixture Particle

Importance of Topic

The combined analysis of particle size distribution and light intensity distribution offers a robust approach for characterizing particulate samples. In practice, verifying sample concentration and detecting unknown or mixed particles prior to and after measurement improves the reliability of laser diffraction analyses across industrial, QA/QC, and research laboratories.

Objectives and Overview

This study aims to evaluate the performance of the SALD-2300 laser diffraction analyzer in resolving single-sized and mixed alumina (Al2O3) powders. Key goals include:

• Assessing particle size distribution for 1 µm and 10 µm samples
• Comparing raw light intensity distribution patterns
• Determining detection limits for minor fractions in binary mixtures

Methodology and Instrumentation

Samples:

• 10 µm alumina (WA#1500): median diameter 10.5 ± 1.0 µm (sedimentation method)
• 1 µm alumina (WA#8000): median diameter 1.2 ± 0.3 µm (electrical sensing zone)

Instrumental Setup:

• Analyzer: SALD-2300
• Accessory: SALD-MS23 dispersion unit
• Dispersing medium: pure water with 0.1% sodium hexametaphosphate
• Sample form: aqueous suspension
• Refractive index: 1.75 – 0.20i

Main Results and Discussion

Single-size Samples:

• 10 µm sample produced a sharp peak at 10 µm in particle size distribution and a characteristic light intensity peak at low scattering angles.
• 1 µm sample showed a distinct distribution peak at 1 µm and intensity maxima at higher scattering angles.

Mixed Samples:

• Binary mixtures of 1 µm and 10 µm alumina were prepared at varying ratios (0–23% 1 µm by volume).
• Accurate quantification of the minor 1 µm fraction was achieved down to approximately 13%–17% volume; below 13%, measured values underestimated true concentration.
• Overlay of light intensity distribution revealed clear shifts in peak patterns corresponding to low-angle (large particles) and high-angle (small particles) sensors. Detection of a 1% minor fraction was possible by monitoring changes in intensity around sensor channels 60–65.

Benefits and Practical Application

This dual-mode analysis enables:

• Pre-measurement concentration checks via light intensity patterns to prevent measurement errors.
• Post-measurement validation of size distribution accuracy, especially for unknown or multi-modal samples.
• Enhanced sensitivity for minor component detection in mixed particulate systems.

Future Trends and Possibilities for Use

Advancements may include:

• Integration of machine learning to classify intensity distribution signatures for complex mixtures.
• Automated real-time feedback on sample concentration and dispersion state.
• Extension of method to non-spherical and highly polydisperse materials.

Conclusion

The SALD-2300 analyzer’s capability to capture both particle size distribution and raw light intensity distribution provides a powerful quality control tool. By correlating intensity patterns with size data, laboratories can ensure measurement validity and detect minor fractions with greater confidence.

References

1. Bonded Abrasive Micro Grain Sizes JIS R6001-1998