Submicron and micrometric polymeric particle dispersions are common in a multitude of applications and products such as pharmaceutical, personal care, food, ceramics, pigments, inks, and cements. A proper dispersion of the particles is necessary to avoid sedimentation, instability, or product failure due to aggregation, oversize, and aging. Classizer™ ONE particle analyser based on patented Single Particle Extinction and Scattering (SPES) method introduces introduces a step forward in the way light scattering is exploited for single particle characterization. Classizer™ ONE provides the information on the different particulate populations in all the intermediate formulation steps and in the final product as required by bottom-up Quality-by-Design formulation, top-down Safe-by-Design approaches and product manufacturing.

Classify

Classify the particle polymeric populations in heterogeneous liquids on the base of single particle optical properties

Analyse

Analyse the numerical particle size distribution and the factors influencing stability and particle behaviour

Quantify

Count the numerical particle concentrations of single particle populations in heterogeneous liquids

Example of application: polystyrene spheres
A polymer that many particle size scientists should be familiar with is polystyrene (PS), which is often used as materials for the preparation of particle size standards employed in particle analysis, and instrument calibration and validation. Classizer™ ONE, based on patented SPES method, is the ideal solution for improving colloids formulations and for verifying product consistency with the target Quality-by-Design final expectations. Depending on the system configuration, sample material and sample preparation, Classizer™ ONE covers a dynamic range of 0.2 – 20 μm, concentration range of 1E5-1E7 ptc/mL @ 0.5-5ccm. External auto-dilution sampler and autosampler available.

(in figure) (TOP) SPES high-resolution characterization of PS 0.5µm spheres dispersed in filtered water at a nominal numerical concentration of 1E6 ptc/mL. About 4 mL of sample have been analysed at 5ccm using a lab syringe pump. About 8000 validated particles populate the SPES CLOUDS map and are employed for the quantitative analysis. The grey tones of the cloud are proportional to relative numerical particle concentration. Location of data in 2D SPES CLOUDS is the optical fingerprint of the sample. Red line represents expected SPES position for PS spheres with different sizes. (BOTTOM) Numerical Particle Size Distribution of the PS sample. Average particle diameter retrieved by EOS Classizer™ software is 0.49 µm @ experimentally measured n=1.60.

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Example of application: heterogeneous samples
In case of heterogeneous samples in terms of the sizes and/or of the refractive indexes, secondary populations could limit, or even preclude any reliable approaches with traditional analytical methods. Thanks to the SPES patented multiparametric approach, Classizer™ ONE discriminates particles basing on optical properties. Heterogeneous samples produce simultaneously more clouds for each particle population which can be easily individually selected, analysed, and compared.

(in figure) Example of EOS CLOUDS for a heterogeneous samples: (TOP) mix of PMMA 600nm and PS 600nm submicron particles. Two separate clouds are detected and can be selected and analyzed separately, as well as for the absolute and relative concentration of each particle population. Red line and blue line are expected trends for PMMA and PS, respectively. (BOTTOM) sample of castor oil emulsion with PS 0.6µm spheres as traceable particles. Two principal and separated populations are detected. Red line represents expected size trend for droplets of castor oil refractive index.

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Discover more > EOS Application Note AN001: Analysis of Polymeric Particles via SPES Technology