The SPES / SPES² measurement allows to effectively discriminate particles based on their optical properties and, in particular, on their effective refractive index.
Once the refractive index has been extrapolated via the EOS CLOUDS, the software automatically retrieves the correct particle size distribution and oversize analysis.
These observables strongly depend on the true refractive index of the particles; using incorrect values leads to unreliable, non-reproducible results.
Thanks to its multiparametric approach, SPES / SPES² directly measure the refractive index, obtaining a true and representative particle size distribution without relying on assumptions or calibrations.

This is not the case with traditional methods such as Dynamic Light Scattering (DLS), Static Light Scattering (SLS) and MultiAngle Light Scattering (MALS), which often depends on complex inversion algorithms and heavy a priori assumptions.

SPES / SPES² also achieves high accuracy and resolution for heterogeneous samples in biological fluids, where the presence of solid content complicates, if not prevents, any characterization measurement with traditional methods.

Experimental Numerical Particle Size Distributions and Cumulant Distributions of a mix of polystyrene standard samples of 0.24µm, 0.46µm, 0.5µm, 0.6µm, 0.7µm, 1µm, 2.0µm, 5µm and 10µm diameters dispersed in filtered water.

Reproducibility is a critical aspect of any analytical method, especially in batch-2-batch quality control applications.
SPES / SPES² measurements of analytical replicates of standard particles are useful for the quantification and the validation of the reproducibility of the method, within the sample preparation error.

SPES / SPES² reproducibility test. Sixteen analytical replicates of polystyrene calibrated spheres of 0.7 µm, diluted 20000 times in milliQ-grade water at 5E6 ptc/mL concentration, from an initial bulk concentration of 1E11 ptc/mL. (top) Particle Size Distribution, (down) Cumulant Particle Size Distributions.

Find out more