FAQ – Frequently Asked Questions

Single Particle Extinction and Scattering SPES are high-resolution analysis techniques which characterize a sample particle by particle. Unlike “ensemble” methods (such as Laser Diffraction or DLS) that provide an average statistical value, SPES measure each individual particle passing through the laser beam. Their unique advantage lie in the simultaneous measurement of three independent optical parameters (extinction, forward scattering, side scattering) for every single event.

Traditional methods as DLS, SLS, and SPOS typically measure only one parameter as the light sccattering or the light extinction, which primarily relates to particle size. By measuring scattering simultaneously, SPES technologies discriminate particles based on their effective refractive index and internal structure. This allows you to distinguish between particles of the same size but different materials (e.g., silica vs. polystyrene).

Yes. This is a core strength of SPES. Because they are sensitive to optical properties, the system can map heterogeneous populations. In a mixture of materials, SPES generates a scatter plot where different populations appear as distinct clusters, allowing for the precise classification and calculation of the relative concentration of each type of particle based on its optical properties.

Absolutely. Since we analyze every single particle, SPES do not suffer from the “masking effect” common in statistical techniques where small particles overshadow larger ones. We can identify, count, and characterize individual aggregates or contaminants even at extremely low concentrations, making SPES an ideal tool for stability and purity testing.

Yes. As a single-particle counting system supported by a high-precision automatic syringe pump, Classizer™ ONE provides the absolute numerical concentration (particles/ml) of each particle population identified in a mixture. This is critical in R&D and QC where weight-based distribution is insufficient for quality control.

Thanks to the sample managers LMS™, the sample autodilutor LAD™, and to the autosampler LAS™, the process is almost entirely automated. The system can handle concentrated samples and dilute them in real-time to the optimal counting condition. This eliminates human error and ensures maximum repeatability of the measurement.

Many extinction-based systems fail if the particle’s refractive index is close to that of the liquid. EOS SPES technologies overcome this by exploiting the interference between the forward scattering and the transmitted beam. Even if a particle is nearly transparent, its scattering signature remains detectable, ensuring accurate counting where other systems see nothing.

Yes. Organic and inorganic materials have different scattering responses. By mapping particles based on multiple independent optical parameters, SPES differentiates between these two or more populations, a task that is impossible for traditional diameter-only analysis.

DLS provides a mean diameter and often fails to detect the early formation of aggregates because it is an ensemble technique. SPES analyses every single particle passing through the measurement volume. While a minimum concentration is required for statistical significance (ideally at least 10⁴ particles/mL), Classizer™ ONE detects and counts these aggregates long before they impact the average data of a DLS, allowing you to predict product instability at a much earlier stage.

The accuracy of concentration data (particles/ml) depends entirely on the precision of the analyzed volume. Our automatic LMS™ liquid sample manager is based on a high quality syringe pump which eliminates the flow fluctuations typical of peristaltic or diaphragm pumps. Furthermore, the LAD™ single point autodiluter ensures the sample is never too concentrated (avoiding coincidence errors) nor too diluted, preserving the integrity of fragile aggregates.

Yes. By tracking both numerical concentration and optical fingerprints, SPES technologies allow you to monitor not just size increase, but also changes in the nature of the population (e.g., the transition from amorphous to crystalline states), making them essential for pharmaceutical and fine chemical R&D.

In many light-scattering or obscuration systems, an air bubble is mistakenly counted as a solid particle. SPES technologies identify the unique “optical signature” of a bubble versus a solid contaminant. This eliminates false positives and ensures your purity data reflects reality.

Yes. SPES technologies are highly effective for multi-phase system analysis. In oil-based samples, they can separately map solid wear particles and emulsified water droplets. This ability to distinguish “solid from liquid” within the same measurement is vital for R&D and predictive QC.

Emulsions (used in cosmetics, pharma, food, fine chemicals, and more) degrade through coalescence or flocculation. While traditional systems only see an increase in “mean diameter,” Classizer™ ONE detects changes in numerical concentration and optical properties distribution. We can spot the emergence of larger droplets long before the emulsion visibly separates.

Yes, within the micron/sub-micron range. Bacteria exhibit specific scattering characteristics compared to inorganic debris. SPES sensitivity allows for the identification of population anomalies which indicate bacterial growth, serving as an early-warning system for process safety.

In microencapsulation, it is critical that the “shell” is intact and no active ingredient is leaked. SPES distinguishes between intact capsules and broken or poorly formed ones by analyzing differences in internal optical structure, providing a level of QC that laser diffraction cannot match.

Certainly. The combination of our high-speed sensors and precise flow management allows Classizer™ ONE and SPES technologies to be integrated directly into production lines or bypasses. This enables 24/7 real-time monitoring of product quality, reducing waste in Industry 4.0 environments.

Principal Component Analysis (PCA) is an advanced statistical method used to manage the vast amount of data generated by SPES. Instead of looking at simple 2D plots, PCA automatically clusters particles based on all their optical properties. This identifies different particle “families” objectively, making the interpretation of complex mixtures intuitive even for non-experts.

Yes. As an Italian engineering firm, we excel in providing tailored solutions. We can customize critical aspects: from the dimensions of the flow channel to the materials of wetted parts (tubing, bulkheads, and connectors) to ensure full chemical compatibility with your specific fluids, we can tailor the software user interface and the introduce personalised algorithms, and more.

Choosing EOS Instruments means investing in metrological traceability, high-quality materials, and direct access to the inventors and designers of the SPES technologies. We offer personalized technical support and the flexibility to adapt our systems to your laboratory or industrial process—a level of responsiveness and long-term reliability that mass-market retailers cannot provide.