Particle size distribution
What is Particle size distribution?
Particle-size distribution relevant to dispersions and batch consistency.
Why do you need this service?
Use particle-size analysis to characterize a relevant dispersed phase and compare batches or formulation changes. The selected technique and preparation should suit the particle range and material.
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Particle size distribution analysis
A distribution describes how sizes vary within a powder, suspension or emulsion. It is more informative than a single average when large particles, aggregates or a broad size range affect appearance, stability or application.
Choosing a measurement technique
Laser diffraction, dynamic light scattering and microscopy characterize different size ranges and sample types. Their outputs are not directly interchangeable: the reported distribution may be weighted by volume, scattering intensity or particle number.
- Powders and pigments: size variation and agglomeration
- Emulsions: droplet populations and changes during storage
- Sunscreen dispersions: particle or aggregate characterization
- Exfoliating materials: size and, with imaging, shape assessment
Dilution, dispersion and sample preparation can alter the structure being measured. The laboratory should document these steps and select conditions that answer the actual formulation question.
Interpreting the profile
Reports may include distribution curves, median size such as D50, distribution width and evidence of multiple populations. The meaning of each metric depends on the measurement basis. Surface-area estimates also depend on assumptions and are not a substitute for a dedicated measurement where one is needed.
Comparisons across batches or stability time points require consistent methods. Particle size alone cannot prove skin gentleness, sunscreen efficacy, penetration or regulatory nanomaterial status.
Applications of particle size distribution studies
Characterizing a dispersion
Dynamic light scattering, laser diffraction or imaging can provide different size-related information where suitable. The report should identify the distribution basis, sample treatment and limits, since dilution or dispersion steps can alter the sample. A droplet or aggregate size is not necessarily a primary-particle size.
Relating size to behavior
Size findings can help investigate texture, sedimentation or emulsion changes alongside other measurements. There is no universal particle-size optimum for stability, skin penetration or maximum sunscreen protection. Performance and safety depend on composition, structure and use as well as the measured distribution.
Characterise cosmetic composition, structure and physical behaviour through active content, particle, pH, flow and molecular-property measurements. Explore another Physicochemical Testing page on cosmetic-labs.com.