• Feb 16, 2024
  • Particle Size
  • By Jorie Kassel

What Does Particle Size Testing by “Best Method” Mean?

In the intricate world of materials science and engineering, the significance of particle size cannot be overstated. The dimensions of particles play a pivotal role in determining the physical, chemical, and mechanical properties of materials, influencing everything from their reactivity to their performance in various applications. However, the task of selecting an appropriate technique for particle size analysis isn’t always straightforward.

With a myriad of methodologies available, each with its own unique strengths and limitations, companies often find themselves navigating a complex landscape in pursuit of accurate and meaningful results. Some materials have guidelines and monographs to help guide companies on how to test, but what if you have a problem with a new material or process that might be solved by knowing the particle size but you don’t know what technique to pursue?

PTL can help determine which technique is applicable to your problem. Our knowledgeable sales team will help you get started and steer the samples toward the best proposed technique based on information you provide. When the path forward is uncertain, our sales team often suggests that, when sending in the samples, you denote on the laboratory service order (LSO) form – “Particle size testing by best method requested.”

What does this mean and how is the “best method” determined?

When a request for “best method” arrives at PTL, our experienced laboratory team examines each specimen. They collaborate closely with the sales team, utilizing provided information, and initiate direct communication with the client to offer comprehensive recommendations.

Initially, our experts employ a standard laboratory microscope to make primary observations, focusing on size, shape, and other pertinent characteristics crucial for technique selection. This gathered information is combined with the context of why the client submitted the material. Key considerations include the identification of outliers, the necessity for a general distribution, and any safety implications associated with the material. Once the lab team makes observations, further discussion between staff and client can commence and we can confirm testing options.

A versatile range of solutions are readily available at PTL whether the goal is conducting comprehensive particle size analyses for pharmaceutical materials, assessing process water or environmental samples for filtration system design, or something in between. We prioritize tailored solutions and avoid imposing a one-size-fits-all approach on a single instrument that may not be suitable for your specific needs.

Whether you are seeking broad particle size determination or require in-depth insights into nanoscale phenomena, our comprehensive suite of instruments ensures that we have the right tools to address your specific requirements.

What are some analyses that are available at PTL?

At PTL, we offer a spectrum of cutting-edge techniques that cater to diverse industry needs. From widely recognized ensemble techniques like Laser Diffraction and Dynamic Light Scattering (DLS), to the intricacies of more specialized particle counting instruments such as image analysis, Single Particle Optical Sensing (SPOS) technique, and Nanoparticle Tracking Analysis (NTA), our repertoire is designed to meet the unique demands of various applications.

What are general considerations for these techniques?

Ensemble Techniques  
The general utility of laser diffraction lies in its ability to provide a comprehensive particle size distribution, offering insights into the size range and distribution of the particles within a given material. Laser diffraction operates on the principle of light scattering, making it adept at capturing data from a broad range of particle types, typically from less than 100 nm up to approximately 3,000 microns, and is generally applicable to wet and dry materials. Although not a resolute technique, laser diffraction is considered the best fit when a broad understanding of particle size distribution on a volume basis is needed, especially in scenarios where an abundance of particles is present.

On a smaller scale, DLS offers a similar resolution as an ensemble technique though its main focus is on particles suspended in a carrier less than a micron influenced by the forces of Brownian motion. The distribution produced by DLS is on an intensity-weighted basis, and the most common output is that of the z-average.

Particle Counters
Particle counters, employing techniques like SPOS and the Coulter principle, are go-to instruments when higher resolution is needed on a more limited macro particle size range. These instruments provide outputs on both a volume and number-weighted basis—which is not possible with an ensemble technique—and enable the detection of outlier populations that may have significant implications for the material’s properties.

SPOS, relying on detection of suspended individual particles through light scattering, and Coulter principle instruments, measuring changes in electrical impedance as particles in suspension pass through a small orifice, contribute to a more nuanced analysis. These advanced instruments offer invaluable insights for industries where precise particle characterization is essential, such as pharmaceuticals, electronics, and materials science.

NTA provides a unique counting benefit in the nanoscale range (less than 1 micron) particles by utilizing the principle of tracking the Brownian motion of individual nanoparticles. Its real-time, high-resolution capabilities make it particularly useful when dealing with small particles by providing outputs on both size and concentration.

Image Analyzers
Lastly, in the particle analysis category, image analysis is a powerful and versatile technique, especially when intricate details such as particle shape are crucial. Unlike traditional methods, which produce particle size results based on an equivalent spherical diameter, image analysis can provide a more comprehensive understanding of a material’s behavior by incorporating shape factors. In addition, if multiple components are within a sample, there’s a good chance these may be able to be differentiated based on applied filter settings.


In the complicated realm of materials science, particle size determination is an essential aspect that significantly influences material properties and performance in various applications. Finding a solution to your problem can feel daunting to navigate. The laboratory team at PTL, with its 30 years of experience and a comprehensive list of techniques, can be the right collaborative partner to solve your problems.

Contact us today to get started!

By Jorie Kassel, Laboratory Division Manager.


Particle Size Distribution

A Particle Size Distribution Analysis (PSD) determines and reports information about the size and range of particles representative of a given material. This analysis can be performed using a variety of techniques; the most suitable will be determined based on the sample properties and question at hand.

Learn More About this Technique