Technical notes and applications

How to choose the right tool for nanoparticle concentration measurements
Comparing concentration measurements between the NanoSight Pro and Zetasizer Ultra; by Jonathan Mehtala, Tuesday, 8th April 2025

“As a Field Application Scientist, I am often asked some form of the following question: Between NanoSight Pro and Zetasizer Advance Ultra, what is the “better” technology to measure particle concentration? My answer to this question is always the same: It depends. 

This is an understandable question, because at first glance, it may not be clear what the differences are between the two instruments. Both Zetasizer and NanoSight instruments use light scattering to measure particles in a liquid and Brownian motion to determine hydrodynamic size. However, the particle concentration measurement principles between the two technologies are fundamentally different. While both instruments measure particle concentration in particles per milliliter (particles/mL), the differences between the two technologies lend themselves to different ideal sample types, mainly relating to size and polydispersity. This blog will explore how these systems compare and contrast to help you make the best choice for your nanoparticle characterization needs. “

For the full article follow this link

When measuring  the  SSA of of low surface area samples free space determination is important.

In BET specific surface area measurements we want to know how much Nitrogen gas adsorbs onto the sample surface. As we can only measure what is dosed we need to know how much is left in the sample tubes as in (Q adsorbed = Q dosed – Q residual). Sometimes the volume above the sample holds more gas than  was adsorbed – so the error are significant. Even using Krypton as a analyte probe doesn’t remove the need to measure FS.

Running a measurement with a non-condensing gas like Helium before or after the BET run allows us to analyse that volume, and further separate it into Warm FS and Cold FS and properly accounting for the missing “residual”.

Micromeritics have also investigated other approaches Free Space Determination with Non-Helium Gases .

Also there are approaches using calculations – Calculating Free Space with Micromeritics Static (Manometric) Adsorption Instruments – Micromeritics

The RIO100 is a unique dual purpose Raman immersion and solids probe.

The HORC Raman RIO 100 is an immersion optic that can collect Raman spectra from turbid liquids. This probe has an adjustable retroreflector and can be added to any Kaiser RXN1 or RXB2 or other quality Raman system.

But remove the reflector and you have complete RIO100 Non-Contact optic that can collect spectra direct from solid surfaces without the usual surface noise.

The overpot below shows Raman spectra captured through the surface of a coated Excedrin tablet, alongside a comparable and conventional Raman spectra from a Research Microscope where the surface was shaved to bare the content.

Non-local density functional theory (NLDFT) 

Micromeritics  has begun the release of a new series of NLDFT models for the characterization of porous carbons. These new models are based upon the leading work of Jacek Jagiello and James Olivier and employ NLDFT techniques for 2-D finite geometry of pores to calculate the pore size distribution of materials from adsorption isotherms. This new technique was first published in the Journal of Physical Chemistry for nitrogen on carbon.

Non-local density functional theory (NLDFT) models are used to determine the porosity of a sample – pore size and pore size distribution – from measured gas adsorption isotherms. Micromeritics provide simple, easy to understand answers to frequently asked questions relating to this topic, supplying the background understanding needed for effective application of this powerful mathematical tool. 

The latest v 3 of the SAIEUS program described on www.nldft.com Non-local density functional theory (NLDFT) modelscan be downloaded from the Micromeritics web site.

Using Polarizers in DLS measurements.

The latest Zetasizer Advanced Pro and Ultra models have an inbuilt filter wheel with a fluorescence filter, a vertical polarizing filter and a horizontal polarizing filter factory installed. The polarising filters bring new capabilities to your DLS measurements and some surprising benefits.

The Vertical polarizer filter can bring you the sort of quality DLS performance you get with glass cuvettes while using low-cost plastic cuvettes – by reducing the scattering noise. For more information on this effect contact Particular Sciences or follow this link. As an example of the effectiveness of this use of polarizers in DLS measurements, look at the graph to the side.

The Vertical Polarizer can also be used during NIBS measurements of concentrated samples to reduce multiple scattering making the measurements at higher concentrations more realistic. This approach was reported by Ragy Ragheb & Ulf Nobbman in Nature’s scientific reports 10, article 217168, 10 Dec 2020

Last but not least, by applying Horizontal Polarization you differentiate Rotational Diffusion from the classic Translational Diffusion we normally use to calculate particle size. This can help identify particles having a shape that is creating some slower than expected diffusion. For more information on this effect contact Particular Sciences or follow this link.

Flow Imaging Microscopy with Light Obscuration

Yokogawa Fluid Imaging Technologies, Inc. manufactures particle analysis instrumentation with digital imaging technology. While the FlowCam series capture the best images possible, their new FlowCam + LO brings extra capabilities to particle detection.

Sub-visible particle detection by flow imaging technologies is classically used in bio-pharma to to view particles and understand more about the nature of any contamination or aggregates.  These labs usually QC their samples on particle counters according to the USP <788> standard. FlowCam + LO tasks flow imaging and light obscuration in one compact and easy to use system.

To learn more about how flow imaging with FlowCam works follow this link.

To download the FlowCam + LO brochure follow this link.

To read the Fluid Imaging informative e-Book please visit the Yokogawa Fluid Imaging Technologies web site and register for your own copy. 

Otherwise please contact Particular Sciences and arrange sample testing or a demonstration.

Images taken on a FIT FlowCam