Particle characterization


Median, mean and cumulative / density distribution

  • Particle size distribution using STEP technology®
     in suspensions, according to ISO 13317 / 13318-2 with LUMiSizer® analytical photo centrifuge and LUMiReader® PSA,
    typical particle sizes of 10 nm to 30 µm or 500 nm to 300 µm

  • Particle size distribution by laser diffraction
    in suspensions, application of Mie and Fraunhofer theory
    typical particle sizes from 0.1 μm to 1200 μm

  • Particle size distribution by means of laser light scattering
    in suspensions, by single particle light scattering analyzer
    typical particle sizes from 0.2 μm to 2 μm

Effective density, skeletal density, density distribution


Determination of the effective density of suspended nanoparticles and microparticles by means of special sedimentation analysis methods.
Determination of the particle migration rate in continuous phases with different densities.


Two methodological approaches:

  • Method of Isopycnic Interpolation

In the suspended state, the particle density corresponds exactly to the density of the liquid suspension medium (Archimedes principle). The particles are dispersed in different solutions with densities close to and below the expected particle density, and the direction and magnitude of the velocity of the moving particles are determined. The effective particle density is determined by interpolation of the liquid density to the particle velocity zero.

  • Multiple - velocity method

The mean effective particle density is calculated from the experimentally determined separation rates of the particles dispersed in two or more liquids with different density (e.g., H2O, D2O, and mixtures of both) using the Stokes equation.


Form descriptors


Particle form (Powdershape®) in powders and suspensions with typical particle sizes from 1 µm to 3000 µm. Forms are described using geometric macroform descriptors according to ISO 9276-6:2008.


Surface Properties
  • Hansen - Dispersibility - Parameter

According to the principle of Hansen - Solubility - Parameter (HSPthe parameters   δD - Dispersion, δP - Polarity und δH - Hydrogen bonding for dispersed particles are determined.

Test solvents are used from the 3D Hansen Space as continuous phases in which the particles are dispersed. The separation kinetics of the particles in each test liquid in LUMiSizer® bzw. LUMiReader® PSA are determined. From these data, the normalization of the sedimentation times of the particles for each test phase is based on the integral extinktion.

The evaluation and classification of the values obtained and the calculation of the HSPs of the particles is carried out with the HSPiP-software.


  • Zeta - Potential

Number of particles per volume


  • Determination of the number of particles in suspensions according to the Coulter principle
    Coulter Counter, typical particle sizes in the range of 1 µm to 50 µm
  • Determination of the number of particles in suspensions by laser light scattering,
    Single particle scattered light analyzer, typical particle size in the range of 150 nm to 2 μm
Mechanical Properties
  • Elasticity and deformability of microparticles and capsules in dispersions, quantification of packing, compression and dilatation behavior by sedimentation analysis with the dispersion analyzer LUMiFuge®
  • Dewatering / consolidation of stable and flocculated suspensions in the original volume concentration by centrifugation with LUMiFuge®
  • Average mass concentration and concentration profiles of particle sediments by means of LUMiReader®- X-Ray
  • Measurement of the burst point and the apparent interfacial tension of microparticles and capsules by means of LUMiTexture, typical particle size range of 500 µm to 5000 µm