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Testing Particle Size by Laser Diffraction

Testing Particle Size by Laser Diffraction

By Jorie Kassel – Laboratory Division Manager

Laser diffraction is a frequently requested technique in the particle characterization industry, but how do you know if it’s right for your material and process?

The experts at Particle Technology Labs have years of experience evaluating powders, semi-solid products, and suspensions and can help determine if this particle sizing technique is right for you.

What is Laser Diffraction?
Laser Diffraction is considered an ensemble technique. This means instead of determining the size distribution one particle at a time (such as with a particle counter), it does so by measuring the light scatter from a cloud or group of particles as it passes through a light source (a laser beam in this case) all at once. The angle of scatter is inversely proportional to the particle size (i.e., small particles scatter light at larger angles). This light scatter, referred to as a diffraction pattern, is then reported as an equivalent spherical diameter within the instrument software based on optical parameters input by the operator. Like many other particle sizing techniques, laser diffraction assumes that the particle is spherical to allow the reporting of a single value…the diameter of a sphere which would scatter the same angle of light detected.

Vaccines and particle size illustration

Vaccine Facts and the Role of Particle Size in Antigen Uptake

With more people getting their COVID-19 vaccines, a larger discourse on vaccination is occurring. Many questions are being presented. How are vaccines made? What is the safety of a vaccine? How is the efficacy of a vaccine determined? How small are vaccine particles? This blog discusses some history of vaccine development and several ways Particle Technology Labs supports the characterization of today’s vaccines.

History of Vaccines

Smallpox was an infectious disease that had a mortality rate of ≤30%. Variolation was developed as a process to inoculate individuals from smallpox (Variola major/minor). Variolation was achieved through the use of powdered smallpox scabs or fluid from pustules being introduced to a patient through scratches on their skin or inhalation through the nose. Variolation was successful in reducing the mortality rate of smallpox to <1% in the variolated patients. However, the variolated patients were able to transmit the virus causing secondary outbreaks.

Say Cheese … a Snapshot of Flowability in Cheese Powder!

William Kopesky – Director of Analytical Services

Moisture Impact on Powders

The physical properties of powders directly impact their processability. This probably isn’t a surprise to anyone, especially if you are previously aware of Particle Technology Labs and what we do for a living! Powder processing involves moving, compacting, packaging, milling, and agglomerating just as a few examples. Particle Technology Labs helps clients on a daily basis investigate powder processing issues as well as predict performance when handling powder products. Any plant manager and production engineer can tell you that moisture has a significant impact on all of the powder processing steps previously mentioned. As the spring season begins here in North America, specifically Chicago, and with summer not far behind…thoughts turn to warmer temperatures, sunny days, the potential to be closer than 6 feet from other individuals and more humid conditions.

Moisture and Cheese

So, you may be asking yourself, “Why is cheese in the title of this blog post? I thought this may be about photography and this guy is talking about powders instead.” Well, here at Particle Technology Labs, it is never a dull moment and we assist with a wide variety of sample types and client issues.

What is the Difference Between Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC)

Chorthip Peeraphatdit – Particle Characterization Chemist IV / Team Leader

Spring is upon us, and with it comes fluctuating weather conditions! You’re enjoying some warmer days, but also a little worried how the extreme changes in temperature may affect your products. Thermal analysis can help you better understand how your materials fare with the changes in temperature. But with so many options in the market, how do you choose?

Today we’ll take a quick look at two most commonly used techniques for thermal analysis: Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC).

What can TGA tell us?

man from Particle Technology Labs doing a test at the poremaster.

What Is Mercury Intrusion Porosimetry and When Is It Used?

Cody Langellier – Laboratory Division Manager

You need to characterize the pore structure of your product, but you’re unsure of how best to do so. You’ve done your research and found a technique called Mercury Intrusion Porosimetry (MIP) but it’s unclear if this is an appropriate test for your needs. How do you proceed?

The experts at Particle Technology Labs (PTL) are happy to guide you completely through the process. We answer commonly asked questions below for those interested in gaining a deeper understanding of MIP:

What is Mercury Intrusion Porosimetry?

Mercury Intrusion Porosimetry is a technique that utilizes mercury to probe the surface accessible pores of a solid or powder material. Mercury is an ideal probe chemical because it is a non-wetting liquid that requires external pressure to fill voids in the surface of a sample. By volumetrically measuring the quantity of mercury forced into the pores of a sample at a given pressure, we can determine the pore size, pore volume and porosity of your sample. Pore size is inversely proportional to the amount of pressure required to force the mercury into the sample pore. Large pores require less pressure to fill with mercury than smaller pores.