Polymeric dispersions of particle mixtures 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 ageing. The Classizer™ particle analyser based on our patented Single Particle Extinction and Scatterings SPES / SPES² / SPESe / μDHM methods introduce a step forward in the way light scattering is employed for single particle characterization. The Classizer™ particle analyser 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.

Example of application: polystyrene spheres
A polymer that many particle size scientists are likely familiar with is polystyrene (PS), which is often used for size standards in particle analysis and instrument calibration and validation. The Classizer™ ONE, based on patented SPES / SPES² methods, 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, the Classizer™ ONE covers a dynamic range of 0.2 – 20 μm and concentration range of 1E5-1E7 ptc/mL @ 0.5-5ccm. External auto-dilution sampler and autosampler are available.

(in figure) (TOP) SPES/SPES² 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 the sample have been analysed at 5ccm using a lab syringe pump. Approximately 8000 validated particles populate the EOS CLOUDS map and are employed for the quantitative analysis. The grey tones of the cloud are proportional to relative numerical particle concentration, while its location is the optical fingerprint of the sample. Red line represents the expected SPES / SPES² position for PS spheres with different sizes. (BOTTOM) Numerical Particle Size Distribution of the PS sample. The average particle diameter retrieved by the Classizer™ ONE software is 0.48 µm with an experimentally measured refractive index of 1.58.

Example of application: heterogeneous samples
In case of samples that are heterogeneous in terms of sizes and/or refractive indexes, the overlap of the different populations can limit or even preclude a meaningful measurement with traditional analytical methods available on the market. Thanks to the SPES / SPES² patented multiparametric single particle measurement, the Classizer™ ONE discriminates particles based on their optical properties. Heterogeneous samples produce simultaneously more clouds on the EOS CLOUDS for each particle population detected, which can be easily individually selected, analysed, counted, and compared. A SPES ahead in Particle Analysis!

(in figure) Example of EOS CLOUDS for a heterogeneous sample: (TOP) mix of PMMA 600nm and PS 600nm submicron particles. Two separate clouds are detected and can be selected and analysed 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 silicon oil emulsion with PS 0.5µm spheres as traceable particles. Two principal and separated populations are detected. The red line represents expected size trend for droplets of silicon oil refractive index.

Discover more > EOS Application Note AN001 Analysis of Polymeric Particle Mixes via SPES/SPES² Technologies